The Marshall Center Papers, No. 5

Counter-Terrorism 

and the 

Use of Force in

International Law

By Michael N. Schmitt

EUROPEAN CENTER FOR SECURITY STUDIES

GEORGE C. MARSHALL
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ISBN 1-930831-08-0
Counter-Terrorism and 

the Use of Force in

International Law

By Michael N. Schmitt

Michael N. Schmitt is Professor of International Law and Director,

Executive Program in International and Security Affairs, George C.

Marshall European Center for Security Studies, Garmisch-Partenkirchen,

Germany.
Foreword

On September 11, 2001, members of the Al Qaeda terrorist organization

seized control of four commercial airliners. They proceeded to fly two into the

World Trade Center and a third into the Pentagon. The fourth aircraft crashed into

the Pennsylvania countryside after passengers heroically attempted to regain

control of it from the terrorists. Nearly 3,000 innocents died in the attacks, which

caused financial losses measured in the billions of dollars.

In response, the United States and Great Britain launched air attacks on

October 7 against Al Qaeda forces based in Afghanistan. The strikes also targeted

the Taliban, a group which controlled most of the country and which had harbored

terrorists for a number of years. As ground operations commenced, other States

joined the anti-terrorist coalition, either by contributing armed forces or granting

access to their territory and facilities. Expressions of support for the USñled

campaign were widespread.

In this Marshall Center Paper, Professor Michael Schmitt explores the

legality of the attacks against Al Qaeda and the Taliban under the jus ad bellum, that

component of international law that governs when it is that a State may resort to

force as an instrument of national policy. Although States have conducted military

counter-terrorist operations in the past, the scale and scope of Operation Enduring

Freedom may well signal a sea change in strategies to defend against terrorism. This

Paper explores the normative limit on counter-terrorist operations. Specifically,

under what circumstances can a victim State react forcibly to an act of terrorism?

Against whom? When? With what degree of severity? And for how long?

Professor Schmitt concludes that the attacks against Al Qaeda were

legitimate exercises of the rights of individual and collective defense. They were

necessary and proportional, and once the Taliban refused to comply with US and

United Nations demands to turn over the terrorists located in Afghanistan, it was

legally appropriate for coalition forces to enter the country for the purpose of

putting an end to the ongoing Al Qaeda terrorist campaign.

However, the attacks on the Taliban were less well grounded in traditional

understandings of international law. Although the Taliban were clearly in violation

of their legal obligation not to allow territory they controlled to be used as a terrorist

sanctuary, Professor Schmitt suggests that the degree and nature of the relationship

between the Taliban and Al Qaeda may not have been such that the September 11

attacks could be attributed to the Taliban, thereby allowing strikes against them in

self-defense under traditional understandings of international law. Were the attacks,

therefore, illegal?

Not necessarily. Over the past half-century the international communityís

understanding of the international law governing the use of force by States has been

continuously evolving. This evolution has been responsive to the changing

circumstances in which international law operates. The attacks of September 11,

iii
and the possibility of similar attacks in the future, represent a momentous and

normatively significant changed circumstance. Thus, international law can be

expected to evolve in response.

Professor Schmitt offers a number of criteria likely to drive future

assessments of the legality of counter-terrorist operations. Such operations must be

necessary; specifically, there must be a sound basis for believing that further

terrorist attacks will be mounted and that the use of force is needed to counter them.

They must also be proportional, that is, limited in nature, targets, level of violence

and location to that required to defeat an on-going attack or prevent any reasonably

foreseeable ones. If conducted in advance of a terrorist strike, counterñterrorist

operations can only be mounted when the potential victim must act immediately to

defend itself and the potential aggressor is irrevocably committed to attack.

However, once a terrorist campaign is underway, acts of selfñdefense are

permissible throughout its course and need not be in response to specific terrorist

actions. Finally, the central purpose of the counterñterrorist operation must be

selfñdefense, not punishment or retribution.

The greatest change in the normative expectations of the international

community is likely to come with regard to State sponsorship of terrorists. Although

no definitive conclusions can be drawn yet regarding the extent and nature of

assistance to terrorists that justifies attacks directly against the State providing it,

clearly the threshold is dropping. Relevant factors include UN Security Council

involvement, the nature of the terrorist group, the type of the support rendered, and

the legitimacy of the government involved. Further, there must be ìclear and

compellingî evidence of the relationship and the State conducting the attack bears

the burden of proof.

Ultimately, Professor Schmitt concludes that no definitive normative verdict

is possible regarding the US and coalition attacks against Al Qaeda and the Taliban.

The attacks against Al Qaeda appear novel, but consistent with the community

expectations existing on September 10. By contrast, the attacks against the Taliban

represent a less than crystalline glimpse of the direction in which the international

law regarding responses to terrorism may be heading. But given the existing

security landscape, he argues that the vector appears positive.

John P. Rose, PhD

Director

George C. Marshall European Center for Security Studies

iv
Counter-Terrorism and the 

Use of Force in International Law

by Michael N. Schmitt

The terrorist attacks of September 11 undoubtedly ushered

in a new era in international security affairs. Although

terrorism has been a tragically prominent feature of the global

condition for most of the past half century, these operations

were quantitatively and qualitatively different than those of the

past. They involved extensive and

sophisticated longñterm planning

by a group that cuts across lines of

nationality and which operates from

within many countries.1 The scale

of the destruction in both human

and physical terms was shocking;

the fact that the attacks and their

aftermath were broadcast live only

served to further exacerbate their psychological impact. That

all 19 terrorists directly involved executed them with great

precision despite the certainty of their own deaths may well

portend a terrifying face of 21st century terrorism ó a genre

of terrorism likely to prove extraordinarily difficult to counter

by traditional means.

Combating this aggravated form of terrorism will require

new cooperative security strategies. Certainly, the Global War

on Terrorism (GWOT) articulated by the United States

represents one such strategy.2 As time passes and opportunities

and threats become clearer, the GWOT will evolve

responsively. Other governments and intergovernmental

organizations are already developing parallel and

complimentary strategies.

Counter-Terrorism and the Use of Force in International Law

Reprinted with permission of the United States Naval War Collegeís 1

International Law Department (from the ìInternational Law Studiesî

series and the Israel Yearbook on Human Rights).

Counter-terrorism

strategy must be

formulated with

great sensitivity to

the evolving norms

of international law

governing force
Michael N. Schmitt

2

Lest the lawlessness inherent in terrorism spread to its

victims, counterñterrorism strategy must be formulated with

great sensitivity to the international law governing the use of

force. Some have suggested that this body of law, including

that facet regarding the right to selfñdefense, is not up to the

task.3 Others counter that effective responses to terrorism and

State ìsupportersî thereof are proving entirely consistent with

existing prescriptive norms.4 This article explores those

norms, specifically the law governing the right of States to

resort to force (jus ad bellum)5 in the context of the response

to the 9/11 attacks. Under what circumstances can a victim

State react forcibly to an act of terrorism? Against whom?

When? And with what degree of severity? It concludes that a

natural evolution in the community understanding of

limitations on the use of force has occurred over the past

decades, such that claims of international lawís present

insufficiency are overblown. However, assertions that the law

as traditionally understood supports a full range of forceful

responses to terrorism equally overstate reality. As is usually

the case, the truth lies between the extremes.

The Relevant Facts

In order to effectively appraise the international law

governing the use of force in counterñterrorism today, and to

acquire a sense for its normative vector, it is necessary to first

paint the factual backdrop. Law tends to be reactive and

responsive to the factual context in

which it operates. Obviously, this is

the case for customary international

law, which relies, inter alia, on State

practice for its emergence. The

same is true, however, for

conventionñbased law. Despite

declarations that international agreements, such as the United

Nations Charter, should be interpreted in accordance with the

Law tends to be

reactive and

responsive to the

factual context in

which it operates
ordinary meaning of their text, it is undeniable that community

understanding of law shifts over time to remain coherent and

relevant to both current circumstances and the global

communityís normative expectations.6

Sadly, the facts of 9/11 are all too familiar. On September

11, 2001, terrorists seized control of four passenger aircraft in

the United States. Two were flown into the Twin Towers of the

World Trade Center in New York City, a third was driven into

the Pentagon in Washington D.C. and the fourth crashed in

Pennsylvania following an heroic attempt by passengers to

regain control from the highjackers. Roughly 3,000 people of

over 80 nationalities perished.

Investigation quickly led authorities to focus their attention

on Usama bin Laden and his Al Qaeda terrorist organization.7

Al Qaeda operates from more than 60 countries through a

compartmentalized network using operatives of numerous

nationalities. By October, the British government felt

sufficiently confident in intelligence reports at its disposal to

release certain facts and conclusions regarding the group.

These were subsequently confirmed by the United States.

Specifically, 10 Downing Street announced that Al Qaeda had

planned and conducted the attacks, that it continued to have

the resources to mount further operations, that US and UK

citizens were potential targets and that ìUsama Bin Laden and

AlñQaíida were able to commit these atrocities because of their

close alliance with the Taleban regime, which allowed them to

operate with impunity in pursuing their terrorist activity.î8

Of particular relevance to the use of force issue is the fact

that Al Qaeda was hardly venturing into terrorism for the first

time on September 11. The organization had allegedly been

involved in the 1993 World Trade center bombing, the 1998

bombings of the US embassies in Kenya and Tanzania (attacks

for which Usama bin Laden has been indicted),9 and the attack

Counter-Terrorism and the Use of Force in International Law

3
Michael N. Schmitt

4

on the USS Cole in 2000; the group had also claimed

responsibility for the 1993 attack on US special forces in

Somalia, as well as three separate 1992 bombings intended to

kill US military personnel in Yemen. Moreover, the United

States Department of State alleges the existence of Al Qaeda

ties to plots (not executed) to kill the Pope, attack tourists

visiting Jordan during the millennium celebration, bomb US

and Israeli embassies in various Asian capitals, blow up a

dozen passenger aircraft while in flight and assassinate

President Clinton.10

That Al Qaeda represents a continuing threat is apparent not

only from its track record, but also from statements

periodically issued by Usama bin Laden himself. The British

governmentís October Press Release cited a number of his

most virulent:

The people of Islam have suffered from

aggression, iniquity and injustice imposed by

the ZionistñCrusader alliance and their

collaborators . . . . It is the duty now on every

tribe in the Arabian peninsula to fight jihad and

cleanse the land from these Crusader occupiers.

Their wealth is booty to those who kill them.

(1996)

[T]errorising the American occupiers [of

Islamic Holy Places] is a religious and logical

obligation. (1996)

We ó with Godís help ó call on every Muslim

who believes in God and wishes to be rewarded

to comply with Godís order to kill Americans

and plunder their money whenever and

wherever they find it. We also call on Muslims

. . . to launch the raid on Satanís US troops and
Counter-Terrorism and the Use of Force in International Law

5

the devilís supporters allying with them, and to

displace those who are behind them. (1998)

[A]cquiring [chemical or nuclear] . . . weapons

for the defence of Muslims [is] a religious duty.

(1998)

Thus, in Al Qaeda we have a determined terrorist organization

that has committed multiple acts of terrorism over the course

of a decade ó acts which resulted in the deaths of thousands

and caused property and financial damage measured in the

billions of dollars ó and views its continuing campaign in

terms of jihad.

The US reaction was swift. Within a week, President Bush

formally proclaimed a national emergency11 and called up

members of the reserve component of the armed forces.12 He

also established the Office of Homeland Security and the

Homeland Security Council in order to facilitate a coordinated

response to the terrorist threat.13 For its part, Congress passed

a joint resolution that authorized the President to ìuse all

necessary and appropriate force against those nations,

organizations, or persons he determines planned, authorized,

committed, or aided the terrorist attacks that occurred on

September 11, 2001, or harbored such organizations or

persons, in order to prevent any future acts of international

terrorism against the United States by such nations,

organizations or persons.î14 Essentially, the United States was

placed on a war footing. Indeed, the President characterized

the attacks as ìan act of war against our country.î15 Thus, the

US government quickly moved beyond a criminal law

enforcement paradigm in determining how to respond to the

attacks.

Almost immediately, the spotlight focused on Taliban

connections to Al Qaeda, which was ìheadquarteredî in
Michael N. Schmitt

6

Afghanistan. Although the United States did not formally

recognize the Taliban as the legitimate government of the

country, they controlled the greatest amount of territory,

including that where Al Qaeda was based.16 Working through

the Pakistani government, which maintained diplomatic

relations with the Taliban, the United States issued a series of

demands. These were set forth publicly in late September

during a Presidential address to a joint session of Congress.

Specifically, the United States insisted that the Taliban:

Deliver to United States authorities all the

leaders of AlñQaíida who hide in your land.

Release all foreign nationals, including

American citizens, you have unjustly

imprisoned. Protect foreign journalists,

diplomats, and aid workers in your country.

Close immediately and permanently every

terrorist training camp in Afghanistan, and

hand over every terrorist and every person in

their support structure to appropriate

authorities. Give the United States full access to

terrorist training camps, so we can make sure

they are no longer operating.17

President Bush made it quite clear that there would be no

negotiation and that he expected immediate compliance.

Moreover, he unambiguously laid out the consequences of

nonñcompliance: ìThey will hand over the terrorists, or they

will share in their fate.î18

Despite the ìnoñnegotiationsî stance, the Taliban expressed

a desire to resolve the matter. These entreaties were rebuffed

and on October 6 the President issued a final public warning to

cooperate.19 The following day the United States and United

Kingdom launched the first phase of Operation Enduring

Freedom, consisting of airstrikes against both Al Qaeda and
Counter-Terrorism and the Use of Force in International Law

7

Taliban targets. The scope and nature of the campaign quickly

expanded to encompass ground and maritime operations.

As required by Article 51 of the United Nations Charter, the

United States promptly notified the Security Council that it

was acting in individual and collective selfñdefense.20 In the

report, the United States asserted that it had ìclear and

compelling information that the Al Qaeda organization, which

is supported by the Taliban regime in Afghanistan, had a

central role in the attacksî and that there was an ìongoing

threatî made possible ìby the decision of the Taliban regime to

allow the parts of Afghanistan that it controls to be used by [Al

Qaeda] as a base of operations.î The purpose of the military

operations was to ìprevent and deter further attacks on the

United States.î Ominously, the United States warned, ìWe

may find our selfñdefence requires further actions with respect

to other organizations and other States.î21 In an address to the

nation, the President echoed the threat contained in the Article

51 notification: ìEvery nation has a choice to make. In this

conflict, there is no neutral ground. If any government

sponsors the outlaws and killers of innocents, they have

become outlaws and murderers, themselves. And they will

take that lonely path at their own peril.î22

Because it had participated in the strikes, the United

Kingdom also transmitted the requisite report to the Security

Council. It announced that the attacks were conducted in

selfñdefense against ìUsama Bin Ladenís Al Qaeda terrorist

organization and the Taliban regime that is supporting it.î The

avowed purpose was ìto avert the continuing threat of attacks

from the same source.î23 Thus, although limiting the scope of

its operations to Al Qaeda and the Taliban, like the United

States it suggested that action was necessary to prevent further

attacks.
Michael N. Schmitt

8

The international reaction to the affair was almost

universally one of outrage over the terrorist acts and support

for the United States. On September 12, the Security Council

passed Resolution 1368 condemning the attacks as

ìhorrifying,î labeling them a threat to international peace and

security, and reaffirming the ìinherent right of selfñdefence as

recognized by the Charter of the United Nations.î24

Resolution 1373, passed on September 28, likewise cited the

right to selfñdefense and laid out steps to combat terrorism,

such as suppressing the financing of terrorism, denying safe

haven to terrorists and their accomplices, and cooperating in

law enforcement efforts.25 Interestingly, the General Assembly

did not refer to selfñdefense in its own resolution on the

attacks.26

Following commencement of the military campaign, the

Security Council passed a number of relevant resolutions. For

instance, on November 14 it issued Resolution 1378, which

expressed support for ìinternational efforts to root out

terrorism, in keeping with the Charter of the United Nationsî;

reaffirmed Resolutions 1368 and 1373 (which had cited the

right to selfñdefense); condemned the Taliban for ìallowing

Afghanistan to be used as a base for the export of terrorism by

the AlñQaíida network and other terrorist groups and for

providing safe haven to Usama Bin Laden, AlñQaíida and

others associated with themî; and expressed support for the

ìefforts of the Afghan people to replace the Taliban.î27 On

December 20 it passed Resolution 1386, which (as with

Resolution 1373) expressed support for rooting out terrorism

in accordance with the Charter, reaffirmed Resolutions 1368

and 1373, and authorized the establishment of the International

Security Assistance Force.28 Reaffirmation of the international

counterñterrorist effort, of previous resolutions, of its prior

condemnation of the Taliban and Al Qaeda and of the fact that

terrorism constitutes a threat to international peace and

security occurred yet again on January 20, 2002 with
Counter-Terrorism and the Use of Force in International Law

9

Resolution 1390.29 In it, the Security Council employed its

Chapter VII authority to impose sanctions on the Taliban and

Al Qaeda, including a freezing of assets, a prohibition of travel

and an arms embargo. 

In none of the resolutions did the Security Council explicitly

authorize the United States, any coalition of forces, or a

regional organization to use force pursuant to Article 42 of the

Charter, as the Council is entitled to do in the face of a ìthreat

to the peace, breach of peace or act of aggression.î30 However,

it is important to note that the Security Council twice referred

to the inherent right to individual and collective selfñdefense

prior to coalition combat operations against the Taliban and Al

Qaeda, that no effort was made to condemn the forceful

response once launched, and that the Council repeatedly

reaffirmed the right to selfñdefense and expressed support for

the international effort to ìroot out terrorismî as those

operations were ongoing.

Beyond the United Nations, the most powerful military

alliance in the world articulated its position in even more

unequivocal terms. The day after the terrorist attacks, NATOís

North Atlantic Council, consisting of Permanent

Representatives of all 19 NATO member States, announced

that if the attacks originated from outside the United States,

they would be ìregarded as an action covered by Article 5 of

the Washington Treaty.î31 Article 5, based on Article 51 of the

UN Charter, provides for collective selfñdefense if any of the

member States suffers an ìarmed attack.î32 Within three

weeks, and following briefings in which US officials provided

ìclear and compellingî evidence that the attacks were not the

work of domestic terrorists, the North Atlantic Council made

precisely that finding and invoked Article 5.33 There was no

mention of whom the defense, which began five days later,

could be directed against. This was a normatively significant

omission given that one of the entities the United States and
Michael N. Schmitt

10

United Kingdom struck on October 7 was a nonñState actor,

whereas the other was a government supportive of that group,

but which did not control it. 

Similarly, the Organization of American States invoked the

collective selfñdefense provisions of the Rio Treaty34

following its finding that ìthese terrorist attacks against the

United States are attacks against all American states.î35

Australia did likewise, citing Article IV of the ANZUS Treaty

in offering to deploy military forces.36 Russia, China and India

agreed to share intelligence with the United States, while

Japan and South Korea offered logistics support. The United

Arab Emirates and Saudi Arabia broke off diplomatic relations

with the Taliban, and Pakistan agreed to cooperate fully with

the United States. Twentyñseven nations granted overflight

and landing rights and 46 multilateral declarations of support

were obtained.37

Once the campaign against Al Qaeda and the Taliban began,

offers or expressions of support flowed in from many sources.

The United Kingdom, as noted, participated directly in the

initial strikes, whereas many other States, such as Georgia,

Oman, Pakistan, the Philippines, Qatar, Saudi Arabia,

Tajikistan, Turkey and Uzbekistan, provided airspace and

facilities. China, Egypt, Russia and the European Union

publicly backed the US/UK operations. The Organization for

the Islamic Conference simply urged the United States to limit

the campaign to Afghanistan,38 while the AsiañPacific

Economic Cooperation Forum condemned terrorism of all

kinds. Neither organization criticized the operations. Australia,

Canada, the Czech Republic, Germany, Italy, Japan, the

Netherlands, New Zealand, Turkey and the United Kingdom

offered ground troops.39 By May 2002, the forces of several

nations, in particular sizable British, Australian, Canadian and

American contingents, were engaged in dangerous ìmopñupî

actions.40
Counter-Terrorism and the Use of Force in International Law

11

Since the counterñterrorism operations began, controversy

has surfaced regarding a number of legal issues. Most notable

among these have been the detention, treatment and proposed

prosecution of the detainees held at US Naval Base

Guantanamo Bay. Also a point of contention, albeit more

muted, is the extent of collateral damage and incidental injury

from the strikes conducted against Al Qaeda and Taliban

targets. And looming on the horizon is a very divisive issue,

i.e., carrying the fight beyond the borders of Afghanistan. Yet,

except in legal circles, and particularly the subñcircle of

academia, there has been de minimus controversy about the

lawfulness of the operations conducted within Afghanistan

under the jus ad bellum. On the contrary, and as illustrated in

the events described above, support for the US and coalition

military response has been strong. The extent to which this

support is grounded in either the law in force (lex lata) or

aspirational law (lex ferenda) is the subject of the remainder of

this article.

The Normative Framework for the Use of Force

The UN Charter expresses the basic prohibition on the use

of force in international law. It provides, in Article 2(4), that

ì[a]ll Members shall refrain in their international relations

from the threat or use of force against the territorial integrity

or political independence of any state, or in any other manner

inconsistent with the Purposes of the United Nations.î41

Within the four corners of the Charter, there are but two

exceptions to this prohibition. The first, set forth in Article 39,

empowers the Security Council to determine the existence of a

threat to the peace, breach of peace or act of aggression and

decide what measures are necessary to maintain or restore

international peace and security. By Article 42, the Council

may turn to military force to resolve these situations in what

are generally labeled ìenforcement operations.î42 States would

provide troops under a United Nations flag, as a coalition of
the willing or individually. Regional organizations are also

authorized to engage in ìenforcementî activities, but only with

the approval of the Security Council.43

The second exception is found in Article 51. It provides:

Nothing in the present Charter shall impair the

inherent right of individual or collective

selfñdefense if an armed attack occurs against

a Member of the United Nations, until the

Security Council has taken measures necessary

to maintain international peace and security.

Measures taken by Members in the exercise of

this right of selfñdefense shall be immediately

reported to the Security Council and shall not in

any way affect the authority and responsibility

of the Security Council under the present

Charter to take at any time such action as it

deems necessary in order to maintain or restore

international peace and security.

Thus, States victimized by an armed attack may not only

defend themselves, but also receive assistance from others in

mounting that defense. They need not await a Council

authorization to act, but are required to report actions taken to

the Security Council, which may itself determine that it needs

to respond in some fashion.

Some commentators assert that additional exceptions to the

prohibition on the use of force lie outside the Charter. Most

frequently cited is a right to humanitarian intervention, a topic

rendered timely by NATOís 1999 intervention in the Federal

Republic of Yugoslavia on behalf of the Kosovar Albanians.44

However, no such purported exception, or at least none that

has garnered any significant support, would apply in the case

of counterñterrorist operations.45

Michael N. Schmitt

12
Despite the seeming expansiveness of the Charter

prohibition, there has been, as will be discussed, growing

support for, or at least a diminishing degree of criticism of,

forceful counterñterrorist operations. Tellingly, they are almost

always justified in terms of the right to selfñdefense, rather

than as an exception to the general prohibition on the use of

force. Perhaps more normatively significant is the fact that

acceptance by other States of their legitimacy, when expressed,

is also usually framed in selfñdefense terms. Thus, while it is

apparent that such activities are increasingly acceptable

politically, it is more appropriate to consider that acceptance as

bearing on the evolution of the norms regarding selfñdefense,

than as exemplars of an emergent exception to a prohibition

generally characterized as comprehensive in nature.

Returning to the Charter, a more apropos inquiry is whether

counterñterrorist operations can fall within the Chapter VII

enforcement framework. That international terrorism may

constitute a threat to international peace and security, as

understood in the Charter use of force context, is

unquestionable. For instance, in 1992 the Security Council,

reacting to attacks against Pan Am Flight 103 (the Lockerbie

case) in 1988 and UTA Flight 722 the following year, affirmed

ìthe right of all StatesÖto protect their nationals from acts of

international terrorism that constitute threats to international

peace and securityî and expressed concern over Libyaís

failure to fully cooperate in establishing responsibility for the

acts.46 The same year, and in response to Libyaís failure to

render the requisite cooperation, the Council reñemphasized

that ìsuppression of acts of international terrorism, including

those in which States are directly or indirectly involved, is

essential for the maintenance of international peace and

security.î It further reaffirmed that ìin accordance with the

principle in Article 2, paragraph 4, of the CharterÖ, every

State has the duty to refrain from organizing, instigating,

assisting or participating in terrorist acts in another State or

Counter-Terrorism and the Use of Force in International Law

13
Michael N. Schmitt

14

acquiescing in organized activities within its territory directed

towards the commission of such acts, when such acts involve

a threat or use of force.î Finally, the Council styled the failure

of Libya to cooperate a threat to international peace and security.47

Similarly, following the 1998 US Embassy bombings in

Nairobi and DarñesñSalaam, the Security Council condemned

ìsuch acts which have a damaging effect on international

relations and jeopardize the security of States.î As it did in

1992, the Council also reiterated the duty to refrain from

ìorganizing, instigating, assisting or participating in terrorist

acts in another State or acquiescing in organized activities

within its territory directed towards the commission of such

acts.î48 The following year, the Council approved Resolution

1269 (1999), which, without being tied to any particular

incident, ìUnequivocally condemn[ed] all acts, methods and

practices of terrorism as criminal and unjustifiable, regardless

of their motivation, in all their forms and manifestations,

wherever and by whomever committed, in particular those

which could threaten international peace and security.î

Indeed, the Security Council characterized the

preñSeptember 11 situation in Afghanistan as one implicating

international peace and security. In October 1999, it ìstrongly

condemn[ed] the continuing use of Afghan territory, especially

areas controlled by the Taliban, for the sheltering and training

of terrorists and planning of terrorist acts, and reaffirm[ed] its

conviction that the suppression of international terrorism is

essential for the maintenance of international peace and

security.î49 It did precisely the same in December 2000. In July

2001, the Council made its position completely unambiguous

by determining that ìthe situation in Afghanistan constitutes a

threat to international peace and security in the region.î50 By

September 2001, therefore, it was abundantly clear that

international terrorism, as well as allowing oneís territory to be

used as a base of terrorist activities, could rise to the level of a
Counter-Terrorism and the Use of Force in International Law

15

ìthreat to the peace.î This being so, the Council is entitled,

pursuant to Article 39, to decide on the appropriate measures

to take to ìmaintain or restore international peace and

security,î and such measures include the use of force.

In the aftermath of the attacks, the Security Council labeled

them threats to the peace. On September 12, 2001, it

ì[s]trongly condemn[ed] in the strongest terms the horrifying

terrorist attacks which took place on September 11, 2001 in

New York, Washington D.C. and Pennsylvania and, regard[ed]

such acts, like any act of international terrorism, as a threat to

international peace and security.î51 On September 28, it did so

again in nearly identical language.52 Meeting at the ministerial

level on November 12, 2001, the Council issued Resolution

1377, in which it declared ìthat acts of international terrorism

constitute one of the most serious threats to international peace

and security in the twentyñfirst century.î53 In subsequent

resolutions on the situation in Afghanistan, it adopted the

practice of reaffirming all previous resolutions, thereby

continuing to characterize the September 11 attacks, as well as

any other act of international terrorism, as a threat to

international peace and security. Such a finding is the sine qua

non of an authorization for a forceful response pursuant to

Chapter VII (with the exception of selfñdefense).

Thus, it is unquestionable that the Security Council could

have elected to mount enforcement operations ó either under

the UN banner or by granting a mandate to member States or

an intergovernmental organization ó in an effort to restore

and maintain international peace and security.54 Since the

demise of the Cold War, the Council has not hesitated to

exercise its enforcement authority, sometimes in quite creative

fashion. Chapter VII enforcement operations have been

conducted in response to such diverse situations as the Iraqi

invasion of Kuwait, the failed State disorder in Somalia,
Michael N. Schmitt

16

fighting resulting from the breakup of Yugoslavia and internal

violence in Indonesia. It has even, in the case of Operation

Deny Flight, authorized a regional security organization,

NATO, to maintain a noñfly zone. And when that same

organization mounted Operation Allied Force to stop human

rights abuses against the Kosovar Albanians by forces of the

Federal Republic of Yugoslavia, ad bellumñbased criticism of

the bombing centered on the fact that the NATO members had

not turned to the Council for authorization to conduct their

humanitarian intervention, rather than on the operation itself.

Perhaps best illustrative of the flexibility with which the

Council has interpreted its Chapter VII authority is creation of

international tribunals to try those charged with human rights

and humanitarian law violations during both international and

nonñinternational armed conflicts.55

In fact, the Security Council has used its Chapter VII

authority to respond to terrorism in the past by imposing

sanctions on both Libya and Sudan for allowing terrorist

organizations to operate from their territory.56 Yet the Security

Council was never asked to issue a mandate in response to the

9/11 attacks and in no resolution did it do so. Although some

commentators have searched for an implied use of force

authorization in the postñattack Security Council resolutions,

such efforts are unnecessary.57 There was no reason for the

Council to issue one. The sole basis for conducting Coalition

operations was selfñdefense, which does not require advance

Council authorization. All the Charter requires is notice

whenever such activities are undertaken. By the terms of

Article 51, an operation in selfñdefense does not deprive the

Council of its ìrightî to respond to the situation, but, by the

same token, that fact does not deprive States of their inherent

right to exercise individual or collective selfñdefense, a form

of armed selfñhelp.58
Counter-Terrorism and the Use of Force in International Law

17

SelfñDefense

As noted, Security Council Resolutions 1368 and 1373 cited

the inherent right to selfñdefense in the specific context of

international terrorism. Further, both the United States and the

United Kingdom notified the Security Council that they were

conducting operations against the Taliban and Al Qaeda

pursuant to their right of individual and collective

selfñdefense. They received verbal and actual support from an

array of States and intergovernmental organizations, and there

was no significant criticism of either the general premise that

States may respond to international terrorism in selfñdefense

or of its invocation in this particular case. However, the

operations that have been mounted against the Taliban and Al

Qaeda raise a number of issues regarding the precise (or not so

precise) parameters of the right to selfñdefense and the nature

of its evolution. Before turning to them though, it is useful to

survey several of those surrounding selfñdefense generally.59

One involves ascertaining whether an action constitutes an

ìarmed attack,î for under Article 51 the right to defend oneself

surfaces only in the face of such an attack. Not all uses of force

rise to this level. For instance, it is arguable that certain

operations that do not involve physical force, such as a

computer network attack, might be a ìuse of forceî [and

thereby contrary to Article 2(4)], but not an ìarmed attack.î60

Similarly, the International Court of Justice, applying

customary international law, held in the Nicaragua case that:

the prohibition of armed attacks may apply to

the sending by a State of armed bands to the

territory of another State, if such an operation,

because of its scale and effects, would have

been classified as an armed attack rather than as

a mere frontier incident had it been carried out

by regular armed forces. But the Court does not
Michael N. Schmitt

18

believe that the concept of ìarmed attackî

includes only acts by armed bands where such

acts occur on a significant scale but also

assistance to rebels in the form of the provision

of weapons or logistical or other support. Such

assistance may be regarded as a threat or use of

force, or amount to intervention in the internal

or external affairs of other States.61

It is therefore the ìscale and effectsî of the act that are

determinative in assessing whether an armed attack is taking

place such that a right to respond in selfñdefense vests. By the

Courtís standard, acts of a ìsignificant scaleî suffice. That

said, the Courtís reference to a mere frontier incident, as well

as the acceptance of actions by other than a Stateís armed

forces, imply that the requisite significance of the scale and

effects is rather low. Border incidents are characterized by a

minimal level of violence, tend to be transitory and sporadic in

nature, and generally do not represent a policy decision by a

State to engage an opponent meaningfully. They are usually

either ìunintendedî or merely communicative in nature. By

negative implication, it would not take much force to exceed

this threshold.

It is possible, then, that a State employing violence will have

ìused force,î62 and in doing so committed an international

wrong, or even engaged in activity constituting a threat to the

peace, breach of the peace or act of aggression (thereby

allowing the Security Council to take cognizance of the matter

under Chapter VII), but not have conducted an armed attack as

that term is understood normatively in the context of

selfñdefense.63 Analogously, actions by nonñState actors (the

applicability of selfñdefense in such situations is discussed

below) might be criminal in nature and/or represent threats to

the peace, breaches of the peace or acts of aggression, but not

be of a scale sufficient to implicate the international law right
Counter-Terrorism and the Use of Force in International Law

19

of selfñdefense. Despite the gaps, however, it would appear

that the level of violence necessary to rise to the level of an

armed attack is markedly low.

Once an armed attack has been launched, the victim State

may respond with force in selfñdefense. However, customary

international law imposes certain requirements on

selfñdefense. In the 19th century Caroline case, Secretary of

State Daniel Webster set out the standard that has since

achieved nearly universal acceptance. According to Secretary

Webster, there must be a ìnecessity of selfñdefence, instant,

overwhelming, leaving no choice of means, and no moment

for deliberationî and the defensive acts must not be

ìunreasonable or excessive.î64 This standard has matured into

the requirements that selfñdefense be necessary and

proportionate. The International Court of Justice confirmed

their existence in both the Nicaragua case65 and the Nuclear

Weapons advisory opinion.66 In the latter case, the Court noted

ìthis dual condition applies equally to Article 51 of the

Charter,î thereby verifying the applicability of the

requirements in both customary and conventional law.67

The principle of necessity requires that the resort to force

occur only when no other reasonable options remain to

frustrate continuation of the armed attack. Obviously, directly

reacting with force to an armed attack that is underway would

seldom be deemed unnecessary. More normatively complex is

the situation where an armed attack has taken place, but for

some reason has paused. Perhaps it has achieved its intended

objectives. Or cooler heads may have prevailed in the

attacking Stateís government. Maybe the government that

ordered the attack has been ousted and a successor government

opposed to the conflict is now in power. Whatever the case,

necessity mandates other than forceful responses whenever

feasible.
Michael N. Schmitt

20

Transposing the standard to terrorism, the question is

generally whether law enforcement operations are likely to be

sufficient to forestall continuation of the armed attack. Such

operations may be undertaken by the victim State, the State

where the terrorists are based, or, for that matter, any other

State. Similarly, if a State in which the terrorists are located

conducts military operations with a high probability of

success, there would be no necessity basis for selfñdefense by

the victim State.

The proportionality principle simply requires that the

response in selfñdefense be no more than necessary to defeat

the armed attack and remove the threat of reasonably

foreseeable future attacks. Yet, it is sometimes wrongly

suggested that the size, nature and consequences of the

response must be proportional to the size, nature and

consequences of the armed attack. As to the size of the attack,

it would be absurd to suggest that there must be an equivalency

of force between the armed attack and selfñdefense. On the

contrary, the attacker typically seizes the initiative, thereby

acquiring an advantage. To successfully defend against an

opponent enjoying such an advantage may take much greater

force than that used to mount the attack.

Requiring equivalency of nature is equally inappropriate.

The International Court of Justice suggested as much by

implication in its Nuclear Weapons opinion. When assessing

the proportionality of the use of nuclear weapons, the Court

opined that ì(t)he proportionality principle may . . . not in

itself exclude the use of nuclear weapons in selfñdefense in all

circumstances.î68 While representing a nonñdecision on the

issue at hand, the Court had admitted the possibility that use of

a nuclear weapon might be legitimate in the face of a

nonñnuclear attack. Scaled down from the nuclear level, such

a criterion remains equally malapropos. By way of illustration,

in responding to a maritime attack the most productive tactic
Counter-Terrorism and the Use of Force in International Law

21

may be to disrupt landñbased maritime command and control

assets. Likewise, in an effort to cause an attacker to desist by

altering his costñbenefit calculations, it may be more effective

to concentrate on targets of particular value to him rather than

those directly involved in the attack.69 In fact, doing so may

well result in a lesser level of violence than would be

necessary to definitively defeat the attacking units themselves.

Surely international law does not mandate titñforñtat

exchanges.

At first glance, a standard of proportionality visñ‡ñvis the

harm caused (or possible) to the victim might seem more

reasonable. In other words, the State engaging in selfñdefense

should not be entitled to cause more harm than it has suffered.

But such a standard ignores the fact that international law

grants States the right to selfñdefense in order that they not be

rendered helpless in the face of an attack. To suggest that a

State cannot use the destructive force necessary to cause an

attacker to discontinue (or to prevent future) attacks, because

the resulting destruction outweighs what the victim State

originally suffered, is to effectively deprive the victim of the

right to selfñdefense.

Finally, there have been suggestions that selfñdefense

operations are disproportionate if they cause more collateral

damage and incidental injury than the civilian casualties and

damage to civilian objects originally suffered by the victim

State. Such assertions have been made in the context of the

current counterñterrorist operations, in which the number of

civilian casualties allegedly exceeds the number of fatalities

resulting from the 9/11 attacks.70 Claims of this nature confuse

the selfñdefense proportionality requirement of the jus ad

bellum with the proportionality principle contained in the law

governing how force may be applied once a state of armed

conflict exists (jus in bello). The latter proportionality

principle forbids attacks ìexpected to cause incidental loss of
civilian life, injury to civilians, damage to civilian objects, or

a combination thereof, which would be excessive in relation to

the concrete and direct military advantage anticipated.î71 But

even by the in bello standard, the correct phenomena to

compare are incidental injuries/collateral damage and military

advantage. The issue is whether or not the military advantage

accruing from an attack justifies the civilian casualties and

damage to civilian objects; there is no balancing of the civilian

suffering on the opposing sides of the conflict.

Restated in the context of terrorism, the proportionality

standard allows only that degree of force necessary to fend off

a terrorist attack and protect oneself from a future continuation

thereof. But the force necessary to achieve this purpose may

far exceed that employed in the attack. Terrorists often operate

in loose networks from dispersed locations, receiving logistic

support in ways intended to mask its nature. Further, they may

be fanatical devotees willing to die for their cause; this makes

it extremely difficult to meaningfully affect their costñbenefit

calculations. Taking them on is a daunting task that typically

requires extremely aggressive measures. 

Beyond necessity and proportionality, the Caroline standard

has also often been deemed to impose an imminency

requirement, i.e., that the attack be ongoing, or at least so

imminent that the victim State has to react almost reflexively

to counter it. This requirement has generated enormous debate

about precisely when it is that an attack becomes imminent

enough to merit ìpreñemptiveî action in selfñdefense. This is

the issue of the appropriateness of ìanticipatory

selfñdefense.î72

Certain commentators who read Caroline narrowly suggest

a high standard of imminence.73 Such a reading logically flows

from Websterís ìinstant, overwhelming, leaving no choice of

means, and no moment for deliberationî verbiage. However,

Michael N. Schmitt

22
Counter-Terrorism and the Use of Force in International Law

23

the nature of combat has evolved dramatically since the time

of the Caroline correspondence. In the 21st century, the means

of warfare are such that defeat can occur almost

instantaneously. Indeed, the linear blitzkrieg strategies of the

Second World War appear slow and unwieldy by todayís

standards, in which the battlespace is fourñdimensional and

effects are generated in fractions of a second.

In such an environment, the most apropos approach is to

concentrate on the underlying intent of the right to

selfñdefense. Its primary purpose is to afford States a selfñhelp

mechanism by which they may repel attackers; it recognizes

that the international community may not respond quickly

enough, if at all, to an armed attack against a State. Yet, the

limitations of necessity, proportionality and imminency play to

the communityís countervailing aversion to the use of violence

by States. Thus, there is a balancing between the Stateís right

to exist unharmed and the international communityís need to

minimize the use of force, which is presumptively

destabilizing.

The most responsive balance between these two interests

lies in permitting a use of defensive force in advance of an

attack if ìthe potential victim must immediately act to defend

itself in a meaningful way and if the potential aggressor has

irrevocably committed itself to attack.î74 This standard

combines an exhaustion of remedies component with a

requirement for a reasonable expectation of future attacks ó

an expectation that is more than merely speculative.

However, what if an attack is ìcompleteî at the time of the

proposed response in selfñdefense? To some extent, this

question bears on the necessity requirement; the termination of

the initial action may allow for other than forceful resolution

of the situation, thereby rendering a use of force in

selfñdefense unnecessary. But the query also touches upon the
Michael N. Schmitt

24

imminency requirement. Must defense against a future attack

be measured by the same standard of imminency as defense

against an initial one?

The answer is ìyes,î but the mere fact that an entity has

attacked once makes it easier to conclude that it will do so

again. After all, the ìpotentialî attackerís state of mind has

now been tangibly demonstrated. Much more to the point, it

may also be reasonable to conclude that the first attack was

part of an overall campaign that in itself constitutes a single

extended armed attack. By this understanding, an

afterñtheñfact reaction to an initial attack constitutes a

response to an ongoing armed attack in which there is but a

tactical pause. The approach reflects the reality of combat, in

which pauses are the norm, not the exception. They may be

necessary for logistical purposes, as a result of weather, due to

enemy responses, pending acquisition of further intelligence,

to leverage surprise, etc. The question is whether the attack

that has occurred is part and parcel of a related series of acts

that will continue to unfold.

Treating a series of actions as a unitary whole makes

particular sense in the context of terrorism. Terrorist

campaigns generally consist of a

series of actions that occur

periodically over extended periods

of time. Moreover, given their

nature, they are very difficult to

defend against while underway ó

the potential target is usually only

revealed by the attack itself, all of

society represents a potential target

thus rendering effective onñtheñspot

defense problematic, the actual

violence may occur after the terrorists have left the scene (as

in a bombing), the terrorists may be willing to die in the attack,

Responding in

self-defense to a

series of attacks

that are part of an

overall campaign

makes particular

sense in the

context of

terrorism
Counter-Terrorism and the Use of Force in International Law

25

and the identity and location of the terrorists may not be

uncovered until after the completion of a particular action. In

fact, in the majority of cases it is only after the attack that the

victim State can mount its response. Therefore, unless one is

willing to deny victim States a consequential right of

selfñdefense against terrorists, it is reasonable to interpret

selfñdefense as permitting the use of force against terrorists

who intend, and have the capability, to conduct further attacks

against the victim. By this interpretation, it is not the

imminency of an isolated action that is relevant, but rather the

relationship between a series of attacks. Once the first of the

related attacks has been launched, the question becomes

whether the victim State has sufficient reliable evidence to

conclude that further attacks are likely, not whether those

further attacks are themselves imminent.

SelfñDefense Against Al Qaeda

ìArmed Attacksî by Terrorists. That the attacks of 9/11

were of sufficient ìscale and effectsî to amount to an armed

attack is tragically selfñevident. However, the selfñdefense

operations launched against the Al Qaeda terrorist network in

Afghanistan raise a number of other interesting issues. The

first is whether an ìarmed attackî can be carried out by a

terrorist group or, stated conversely, whether selfñdefense can

be conducted against one.

Some commentators have suggested that until 9/11, the

understanding of selfñdefense against an armed attack was

essentially limited to aggression by States.75 But Article 51

makes no mention of the nature of the entity that must mount

the attack that in turn permits a forceful response in

selfñdefense. This omission is particularly meaningful in light

of the fact that Article 2(4)ís prohibition on the use of force

specifically applies only to actions by Members of the United

Nations, all of which are States. That one key provision on the
use of force [2(4)] includes a reference to States, whereas

another (51) does not, implies that the latter was not meant to

be so limited. This distinction makes sense in the Charter

context. The Charter was meant to govern State behavior, but

in doing so it both limits what States may do and empowers

them. Thus, in 2(4) it restricts a Stateís resort to force, but in

51 authorizes it to use force in the face of armed attack. It

would make no sense to limit the authorization to attacks by

States because at the time the Charter was drafted, that was the

greater threat.

Article 39 is similarly devoid of reference to State action

when charging the Security Council with responsibility for

deciding on the measures to take in the face of a threat to the

peace, breach of the peace or act of aggression. In the various

resolutions regarding the events of 9/11 (and those resulting

from it), the Council characterized the situation as a threat to

international peace and security. Moreover, it specifically

noted that as a general matter terrorism constituted such a

threat. While Article 39 does not directly address selfñdefense

and armed attacks, both it and Article 51 fall within Chapter

VII, which is entitled ìAction with Respect to Threats to the

Peace, Breaches of the Peace, and Acts of Aggression.î

Considering these related points visñ‡ñvis Articles 39 and 51,

it is reasonable to conclude that the entire chapter deals with

actions that threaten international peace and security, whatever

the source.

Moreover, recall that Security Council Resolutions 1368

and 1373, which both cited the inherent right of selfñdefense,

were issued before the counterñterrorist campaign began and

at a time when suspicion was focused on an international

terrorist group as the culprit. In particular, recall that

Resolution 1368 passed the very day after the attack, when no

one was discussing the possibility that a State may have been

behind the actions. This indicates that the Councilís

Michael N. Schmitt

26
understanding of selfñdefense includes defending against

armed attacks by nonñState actors. 

State practice in the aftermath of 9/11 further supports the

applicability of selfñdefense to acts by nonñState actors. No

voices were raised claiming that either the customary right of

selfñdefense or Article 51 was limited to the context of State

actions. On the contrary, there were very visible illustrations,

such as NATOís invocation of Article V for the first time in its

existence, of the fact that most States viewed 9/11 as an armed

attack meriting actions in selfñdefense; in no case, was there

any suggestion that the right was dependent on identifying a

State as the attacker. Lest there be any question on this point,

once the selfñdefense actions commenced against both a State

and a nonñState actor on October 7, the dearth of controversy

over using selfñdefense against nonñState actors persisted.76 In

fact, postñOctober 7 Security Council resolutions went so far

as to urge member States to ìroot out terrorism, in keeping

with the Charter of the United Nations.î77

Necessity and the Impact of Law Enforcement

Alternatives. It is interesting to note that support for using

force was widely evident despite the fact that a logical

alternative to selfñdefense existed ó criminal law

enforcement.78 After all, the September 11 terrorist acts

constituted a variety of criminal offenses under the laws of a

number of jurisdictions. Because it allows for universal

jurisdiction, of particular significance is the offense of crimes

against humanity.79 Further, relevant international law

instruments that bear on the incident (or analogous terrorist

incidents) include, inter alia, the Hague Convention for the

Suppression of Unlawful Seizure of Aircraft, the Tokyo

Convention on Offences and Certain Other Acts Committed on

Board Aircraft, the Montreal Convention for the Suppression

of Unlawful Acts against the Safety of Civil Aviation, and the

International Convention for the Suppression of Terrorist

Counter-Terrorism and the Use of Force in International Law

27
Bombings.80 Although these treaties do not directly criminalize

the actions, they often require criminalization at the domestic

level and/or set forth mutual law enforcement cooperation and

extradition procedures.81 Under US federal law, the acts

violated certain sections of the Antiterrorism Act of 199082 and

the US statutes implementing the Montreal Convention.83 Of

course, specific elements of the attacks violated the criminal

law of the US states (and the District of Columbia) where they

occurred, such as the prohibitions on murder and the various

forms of accomplice participation.

It is apparent, therefore, that the international community

does not view the applicability of a criminal law enforcement

regime as precluding a response in selfñdefense to an armed

attack by terrorists. That said, the prospect of law enforcement

bears on the issue of whether particular acts of selfñdefense are

necessary. Recall that necessity requires an absence of

reasonable alternatives to the defensive use of force. In this

context, then, the State may only act against the terrorists if

classic law enforcement reasonably appears unlikely to net

those expected to conduct further attacks before they do so.

One must be careful here. There is no requirement for an

expectation that law enforcement will fail; rather, the

requirement is that success not be expected to prove timely

enough to head off a continuation of the terrorist campaign. Of

course, if no further attacks are anticipated, the necessity

principle would preclude resort to armed force at all, since

selfñdefense contains no retributive element.

In this case, the necessity of resort to force was obvious

despite the nearly global law enforcement effort to identify and

apprehend members of the Al Qaeda network and prevent

further attacks. Recall that Al Qaeda had been implicated in

numerous prior acts of terrorism, most notably the 1998 East

African embassy bombings, and was at the time of the 9/11

attacks already the target of a massive international law

28

Michael N. Schmitt
Counter-Terrorism and the Use of Force in International Law

29

enforcement effort. Nevertheless, law enforcement failed to

prevent the tragic events of September 11. That is hardly

surprising. Al Qaeda is a shadowy, looseñknit terrorist

organization in which cells operate with substantial autonomy

from scores of countries. The complexity of coordinating law

enforcement efforts in the face of widely divergent

capabilities, domestic laws and national attitudes was

daunting. Further, Al Qaeda was headquartered in

Afghanistan, then ruled by a government seemingly oblivious

to international pressure to deny Al Qaeda its main base of

operations. Simply put, there was no guarantee that even a law

enforcement effort that was proving successful against much

of the organization could effectively eradicate the threat of

another major attack. At the same time, aggressively attacking

the senior leadership and denying it a base of operations

promised great returns in alleviating the threat, far greater than

would likely be realized by law enforcement in a comparable

period. And it must be remembered that the clock was ticking.

As the United States and its coalition partners planned their

response, warnings of imminent attacks flowed through

intelligence channels with great frequency.

Proportionality. The second core requirement of

selfñdefense, that of proportionality, also limits when a State

may resort to selfñdefense in responding to a terrorist act.

Whereas necessity asks whether the use of force is appropriate,

proportionality asks how much may be applied.

Like necessity, proportionality is affected by the prospect of

law enforcement activities. Even if armed force is necessary,

the extent of that force may be diminished by ongoing or

future law enforcement activities. In counterñterrorist

operations, law enforcement and military force can act

synergistically, thereby reducing the level of force that needs

to be applied (and affecting its nature). For instance, law

enforcement disruption of a number of terrorist cells within an
organization may lessen the extent (number, location, etc.) of

military strikes that need to be conducted. That is exactly what

happened in the aftermath of 9/11. Thousands of potential

terrorists were arrested or detained worldwide, thereby

dramatically reducing the need to resort to force in countering

future terrorism. 

Were the strikes against Al Qaeda proportionate, particularly

in light of the extensive parallel law enforcement campaign?

Clearly, they were. Al Qaeda forces in Afghanistan numbered

in the thousands and were widely dispersed. Moreover, to be

disproportionate, the use of force would have had to be

excessive in relation to the degree of force actually needed to

prevent continuation of Al Qaedaís terrorist campaign. As of

June 2002, Al Qaeda forces remain in the field, periodically

engaging coalition forces, albeit in small unit fashion. Further,

intelligence sources have reported that midñlevel Al Qaeda

operatives have pulled the organization back together again

and are forging alliances with other terrorist groups. The

organization reportedly ìis as capable of planning and carrying

out potent attacks on U.S. targets as the more centralized

network once led by Osama bin Laden.î84 So, despite the

success of international law enforcement and military efforts,

Al Qaeda remains a very viable threat, continuing to operate

from bases in any number of countries. The group may have

been gravely wounded, but it would be highly premature to

contend the wounds are fatal.

That said, the increasing effectiveness of international

counterñterrorist law enforcement efforts and the fact that the

fight may now need to be taken outside the borders of

Afghanistan do raise questions regarding the proportionality of

future military efforts. Using an extreme example for the sake

of illustration, one might question the proportionality of a

largeñscale military operation mounted into an uncooperative

State which refuses to hand over a small number of lowñlevel

Michael N. Schmitt

30
operatives. The action might be necessary in the sense that

diplomacy and law enforcement offered slim prospects of

taking them out of the terrorist network, but the extent of the

use of force would appear to be more than reasonably required

to accomplish the objective.

Imminency. As noted above, it would make little sense to

evaluate each terrorist attack individually in every case. Doing

so would deny the reality that most conflict, even conventional

conflict between States, is a series of engagements, with

contact repeatedly made and broken. This being so, in many

situations it may be reasonable to conclude that an attack was

merely the opening shot in an overall campaign that in itself

constitutes a single ongoing armed attack. 

That is exactly the case with regard to the 9/11 attacks. Al

Qaeda had been involved in terrorism against US assets for a

decade, terrorism that resulted in extensive property damage,

loss of life and injury. Although there was often a hiatus

between attacks, they did occur with some regularity. In light

of this record, it is absurd to suggest Al Qaeda would terminate

the campaign after achieving its most significant victory; logic

would impel just the opposite conclusion. Additionally, not

only did Al Qaedaís own statements style continued attacks as

a religious duty, one of the organizationís central objectives,

withdrawal of US and coalition forces from Islamic territory,

remained unfulfilled. Since 9/11, multiple Al Qaeda related

plots have been uncovered or foiled, most recently that

involving use of a ìdirty (radiological) bombî against a US

population center.85 Thus, it is not necessary to speculate on

whether further attacks were likely and imminent on October 7;

they clearly were (and remain so). 

CrossñBorder CounterñTerrorist Operations. While it is

appropriate to extend selfñdefense to acts committed by

nonñState actors, and though the availability of criminal law

Counter-Terrorism and the Use of Force in International Law

31
enforcement responses does not preclude doing so, since

nonñState actors possess no territory as a matter of

international law (they may in fact), can the victim State enter

another Stateís territory in order to conduct selfñdefense

operations? The answer requires balancing the rights and

duties of the respective States involved. The State in which the

terrorists are located has a right of territorial integrity. This

wellñestablished customary international law right creates

corresponding duties in other States. For instance, Article 2(4)

of the UN Charter prohibits the threat or use of force against

the ìterritorial integrity . . . of any State.î86 Commentators

generally agree that the prohibition extends to any

nonñconsensual penetration of a Stateís territory, not simply

those intended to seize parts of that territory.87

Nonñcompliance may amount to an act of aggression.88

However, the State victimized by terrorism has a right to

selfñdefense. No one would dispute that a State forfeits a

degree of its right to territorial integrity when it commits acts

that vest the right to selfñdefense in another State, at least to

the extent necessary for selfñdefense to be meaningful. Thus,

an armed attack by State A may justify the crossing of State Bís

military forces into State A to put an end to the attack.

Lest the right to selfñdefense be rendered empty in the face

of terrorism, in certain circumstances the principle of

territorial integrity must yield to that of selfñdefense against

terrorists. Putting aside the issue of when the acts of terrorists

may be ascribed to a State, thereby justifying selfñdefense

directly against that State, the balancing of selfñdefense and

territorial integrity depends on the extent to which the State in

which the terrorists are located has complied with its own

responsibilities visñ‡ñvis the terrorists.

As John Basset Moore noted in the Lotus case, ìit is well

settled that a State is bound to use due diligence to prevent the

32

Michael N. Schmitt
commission within its dominions of criminal acts against

another nation or its people . . . .î89 This principle has been

reflected in numerous pronouncements on terrorism. For

instance, the 1970 Declaration on Friendly Relations urges

States to ìrefrain from . . . acquiescing in organized activities

within its territory directed toward the commission of [terrorist

acts in another State],î90 a proscription echoed in the 1994

Declaration on Measures to Eliminate Terrorism.91 In the

context of the instant case, recall the 1999, 2000 and 2001

Security Council resolutions condemning the Talibanís

willingness to allow territory they controlled to be used by Al

Qaeda.

Should a State be unable or unwilling to comply with this

obligation, the victim State is then permitted to enter the

territory of the State where the terrorists are located for the

limited purpose of conducting selfñdefense operations against

them. This is only logical, since the unwillingness or inability

of State A to comply with the requirements of international law

cannot possibly be deemed to deprive State B of its authority

to defend itself against an armed attack, the seminal right of

the Stateñcentric international normative architecture. Of

course, all requirements of selfñdefense must be met. There

must be an ongoing armed attack (or armed campaign), no

reasonable alternative to the penetration of State Aís territory

for the purpose of using force against the terrorists can exist,

and the force used has to be limited to that necessary to

accomplish the defensive objectives. Once those objectives are

attained, State B must immediately withdraw because at that

point there is no right of selfñdefense to justify its ìviolationî

of State Aís territorial integrity. Further if, during the

selfñdefense operations, State A takes actions that comply with

its obligation to deny use of its territory to terrorists, State Bís

right of selfñdefense will diminish accordingly. Finally, State

A may not interfere with the selfñdefense operations, as State

B is simply exercising a right under international law. Since

Counter-Terrorism and the Use of Force in International Law

33
State Bís use of force is lawful, any other Stateís use of force

against it would constitute an ìarmed attack.î92

In fact, there have been numerous instances of States

exercising this selfñhelp right of selfñdefense. In the aftermath

of the coalition operations against Al Qaeda, the most often

cited has been US General John Pershingís unsuccessful 1916

foray into Mexico after Pancho Villa and his bandits killed 18

Americans in New Mexico. At the time, Mexico was in the

midst of a revolution and, thus, incapable of effectively

controlling Villa. Note that the Mexican government asked the

US forces to withdraw three months after they entered

Mexican territory, a demand refused on the basis of Mexicoís

inability to police Villa. Similarly, during the Vietnam conflict,

the United States conducted aerial and ground attacks against

enemy forces that had sought refuge in Cambodia. Although

criticized widely, such criticism was arguably more the

product of general antiñwar fervor, than concern over the

legality of the operations.93 In another example, Israel

conducted airstrikes against PLO facilities in Tunisia during

1985 on the grounds that the PLO was using Tunisia as a base

of operations for terrorist attacks on Israel ó with the

acquiescence of the Tunisian government.94 The Security

Council, with the United States abstaining, condemned the

bombings as an ìact of armed aggression perpetrated by Israel

against Tunisian territory in flagrant violation of the Charter of

the United Nations, international law and norms of conductî in

a 14ñ0 vote.95 Whether concern centered on the alleged

violation of international law or on the fact that the operation

posed a ìthreat to the peace and security in the Mediterranean

regionî96 (and on general hostility to Israel) remains an open

question. 

Political unacceptability instead of normative concern also

drove most international criticism of South Africaís operations

against African National Congress groups based in Angola

Michael N. Schmitt

34
during the 1970s.97 Similarly, the international community was

unsupportive as Turkey mounted regular incursions into

Northern Iraq against Kurdish terrorists throughout the 1990s.

As in the South African case, opposition arguably was driven

by factors other than the legal acceptability of crossing into

Iraq. At the time there was de minimus concern over violation

of Iraqís territorial integrity, as Iraqi forces and government

officials were already excluded from the area due to their

suppression of the Kurds. Rather, criticism most likely derived

from irritation over interference with the relief and noñfly

operations in Northern Iraq98 and concern over a track record

of human rights abuses against the Kurds during Turkish

military operations conducted in Southeastern Turkey.99 

Most recently, the United States launched raids on terrorist

facilities in Afghanistan and Sudan following the 1998

bombings of the US embassies in Nairobi and

DarñesñSalaam.100 Although the cruise missile strike against the

al Shifa pharmaceutical plant in Sudan (it was allegedly

involved in chemical weapons production) was criticized, most

censure surrounded the alleged invalidity of the claim of a

connection between the plant and international terrorism, not the

violation of Sudanese territory;101 the attacks against Al Qaeda

training bases in Afghanistan evoked little condemnation. Nor

did the 1999 pursuit of Hutu guerrillas in the Democratic

Republic of Congo by Ugandan forces following a massacre of

foreign tourists,102 although the internationalization of the

conflict did draw international concern and resulted in the

dispatch of a peacekeeping force by the Security Council.103

Of greatest normative relevance on the issue of crossñborder

counterñterrorist operations is the famous Caroline incident

cited above in regard to the core requirements of selfñdefense.104

Recall the facts. In 1837 a rebellion was underway in Canada

against the British. Some of the rebels were based in the

United States. The British attempted to negotiate with the

Counter-Terrorism and the Use of Force in International Law

35
American side, in particular the Governor of New York, to no

avail. At that point they mounted a small raid (80 men) into the

United States where they seized the Caroline, a vessel used by

the rebels and their supporters. The ship was set ablaze and

sent over Niagara Falls.

The incident generated a fascinating correspondence over

the next several years between the British Foreign Office and

the United States Department of State. The issue in dispute,

though, was not whether the British could legitimately cross

into the United States for the limited purpose of attacking the

rebels. Instead, controversy focused on the circumstances

permitting them to do so, and how. As Lord Ashburton, the

Foreign Minister, wrote to his US counterpart, Daniel Webster:

I might safely put it to any candid man,

acquainted with the existing state of things, to

say whether the military commander in Canada

had the remotest reason, on the 29th day of

December, to expect to be relieved from this

state of suffering by the protective intervention

of any American authority. How long could a

Government, having the paramount duty of

protecting its own people, be reasonably

expected to wait for what they had then no

reason to expect?105

Ashburtonís premise that crossing the border was proper in the

absence of effective action by the authorities where the rebels

were based went unchallenged, with Webster simply asserting

that the action had been excessive in the particular

circumstances of the case.106

Therefore, quite aside from the trinity of selfñdefense

criteria, Caroline supports the principle that a State suffering

attack from nonñState actors in another may, after seeking

assistance from that State (assuming the requested State is

Michael N. Schmitt

36
capable of doing so), enter its territory for the limited purpose

of preventing further attacks, although its actions must be

necessary and proportional. State practice seems guardedly

consistent. Objections to such limited cases as have occurred

are usually attributable to political, vice normative,

motivations. Of course, in fairness, the same could be said

regarding the relative absence of criticism when penetrating

the territory of ostracized States, such as Afghanistan, in

operations against organizations which enjoy no consequential

support from members of the international community, such as

Al Qaeda. The better interpretation, however, is that, as a

general matter, State practice, beginning with the Caroline

case, supports the approach posited. 

Do US and coalition operations in Afghanistan comport

with this standard? Recall the Security Councilís preñ and

postñ9/11 demands that the Taliban cease allowing territory

they controlled to be used as a terrorist base and that they

cooperate in bringing Usama bin Laden and Al Qaeda to

justice. Recall also the US demands that the Taliban

unconditionally surrender bin Laden and other Al Qaeda

leaders and grant the United States sufficient access to terrorist

bases to ensure their inoperability. In reply, the Taliban regime

first stated it wished to see the evidence linking bin Laden to

the 9/11 attacks.107 As the likelihood of US strikes drew closer,

the Taliban indicated that they had Usama bin Laden and

might be willing to negotiate, possibly about turning him over

to a third country. The United States again stated that only an

unconditional surrender of bin Laden and other Al Qaeda

leaders would suffice.108 After the coalition attacks

commenced, the Taliban renewed the offer. However, the US

administration maintained its noñnegotiation stance.109

Were the US demands, particularly in that they were

unconditional, sufficient? It might be argued that no demand at

all was necessary, for on multiple occasions the Security

Counter-Terrorism and the Use of Force in International Law

37
Michael N. Schmitt

38

Council had insisted that the Taliban comply with the

measures sought by the United States. Consider, for instance,

the following unambiguous language in Security Council

Resolution 1333 (2000): 

[The Security Council] Demands . . . that the

Taliban comply without further delay with the

demand of the Security Council in paragraph 2

of resolution 1267 (1999) that requires the

Taliban to turn over Usama bin Laden to

appropriate authorities in a country where he

has been indicted, or to appropriate authorities

in a country where he will be returned to such a

country, or to appropriate authorities in a

country where he will be arrested and

effectively brought to justice;

Demands further that the Taliban should act

swiftly to close up all camps where terrorists

are trained within the territory under its control,

and calls for the confirmation of such closures

by the United Nations, inter alia, through

information made available to the United

Nations by Member States in accordance with

paragraph 19 below and through such other

means as are necessary to assure compliance

with this resolution . . . .110

Extended nonñcompliance with the Security Council

demands arguably provided a good faith basis for determining

that further exhortations would prove fruitless. However, the

Councilís insistence was made in the context of cooperative

law enforcement (albeit in the face of a threat to international

peace and security) rather than selfñdefense. Therefore, the

most defensible position is that while nonñcompliance

strengthened the political case for action by the Security
Council under Chapter VII, a separate demand was required

for action by a State pursuant to the right to selfñdefense.

As noted, the United States made one. Unconditionality was

certainly reasonable in the circumstances. The United States

had just suffered a horrendous terrorist attack, with every

reason to believe more were imminent. The Taliban request for

evidence of Al Qaedaís complicity might have made sense but

for the previous Security Council resolutions, which clearly

rendered the request superfluous. Moreover, the United States

government, which had been conducting talks with the Taliban

since 1996 over the presence of Al Qaeda in Afghanistan, had

previously provided evidence of Al Qaeda responsibility for

the 1998 bombings of the two US embassies in East Africa ó

at the request of Taliban officials.111 The provision of that

evidence, and the continuing talks, had no discernible effect on

the Talibanís continued harboring of the terrorist organization.

Additionally, unless the Taliban regime controlled Al Qaeda

absolutely, which it did not, post 9/11 negotiations would

merely have extended the window of vulnerability for the

United States. If the right to selfñdefense was to be meaningful

in these circumstances, the United States needed to act as

quickly as possible. This meant that either the Taliban should

have complied with the demands promptly or acknowledged

they lacked the capability to do so and stood aside as the

United States entered Afghanistan to engage Al Qaeda.

In other words, the adequacy of a request to the State in

which terrorists are located, as well as the sufficiency of the

response thereto, must be assessed contextually. Have there

been prior requests? For what? What is the nature of relations

between the requesting and requested State? Between the

terrorist group and the State in which it is located? What

capability does the requested State have to counter or control

the terrorists? What is its track record in doing so? What are

the nature and the imminency of the threat by the terrorists

against the requesting State? Under the circumstances, the US

Counter-Terrorism and the Use of Force in International Law

39
decision to attack Al Qaeda on October 7, despite Taliban

quibbling over the US request to turn over members of the

organization, was reasonable and legally defensible.

There are two other circumstances in which it is

unquestionable that one State can enter the territory of another

to conduct defensive counterñterrorist operations. The first is

upon invitation, though any such operation would have to

comply with the relevant provisions of human rights and

humanitarian law, as well as any conditions imposed by the

host State.112 Obviously, that did not occur in the case of

Afghanistan. More problematic is the situation in which the

terrorist group acts on behalf of the State such that its attacks

can be deemed those of the State itself. As in traditional armed

attacks by a State actor, the sole question regarding the

penetration of the attackerís territory is whether crossñborder

operations are necessary, proportional and in response to an

armed attack. To the extent the State could be attacked in

selfñdefense, so too can the terrorist group that actually

executed the armed attack. The issue of Taliban support for Al

Qaeda is considered in the following section.

Summarized, the campaign against Al Qaeda in Afghanistan

is a legitimate exercise of the right to individual and collective

selfñdefense. The right extends to armed attacks from

whatever source, the 9/11 attacks

met the threshold requirement of

being ìarmed,î crossing into

Afghanistan was appropriate once

the Taliban failed to police the

territory they controlled, the attacks

were necessary and proportionate,

and they occurred in the face of an imminent, credible

continuation of an Al Qaeda campaign that had been underway

for a period measured in years.

Michael N. Schmitt

40

Campaign against

Al Qaeda is a

legitimate exercise

of the right to

individual and

collective defense
Operations Against the Taliban

In his address to a Joint Session of Congress on September

20, President Bush uttered his ominous warning that ì[e]ither

you are with us, or you are with the terrorists. From this day

forward, any nation that continues to harbor or support

terrorism will be regarded by the United States as a hostile

regime.î113 When the attacks began, the United States cited the

Talibanís decision to ìallow the parts of Afghanistan that it

controls to be used by [Al Qaeda] as a base of operation,î a

policy which the Taliban refused to alter despite repeated

entreaties to do so, as justification for their actions.114 It should

be noted that in June 2001 the United States had already

warned the Taliban regime that it would be held responsible

for any terrorist acts committed by terrorists that it was

sheltering.115

The United Kingdom has released the most extensive

information to date regarding the relationship between Al

Qaeda and the Taliban.116 Al Qaeda provided troops, weapons

and financing to the Taliban for its conflict with the Northern

Alliance. The organization was also reportedly involved in the

planning and execution of Taliban operations, assisted in

training Taliban forces, and had representatives assigned to the

Taliban command and control structure. Additionally, Al

Qaeda was a source of ìinfrastructure assistance and

humanitarian aid.î117 In return, the Taliban granted Al Qaeda

safe haven and a base for its terrorist training camps;

essentially, Al Qaeda enjoyed free rein to do as it pleased in

Taliban controlled territory. Further, the two groups

cooperated closely in the drug trade, with the Taliban

providing security for Al Qaedaís drug stockpiles.118 Was this

relationship such that conducting military operations against

the Taliban on October 7 was a legitimate exercise of the use

of force by the United States and United Kingdom?

Counter-Terrorism and the Use of Force in International Law

41
State Responsibility. Unfortunately, there has been much

confusion surrounding the relationship between Taliban

obligations and the attacks mounted against them on October 7.

In the discussion of selfñdefense against Al Qaeda, it was

noted that the Taliban had a duty to keep their territory from

being used as a base of terrorist operations. Failure to comply

with that duty in part justified penetrating Afghan territory

when attacking Al Qaeda, albeit only to conduct operations

against Al Qaeda. If the Taliban were incapable of stopping Al

Qaeda, then they would incur no responsibility for their failure

to address the situation. 

On the other hand, if capable, but unwilling, the Taliban

would be responsible for their failure under the international

law of State responsibility.119 The duty to desist from assisting

terrorists in any way is manifest. In 1996 the General

Assembly articulated this duty in the Declaration on the

Strengthening of International Security. Specifically, it stated

that ìStates, guided by the purposes and principles of the

Charter of the United Nations and other relevant rules of

international law, must refrain from organizing, instigating,

assisting or participating in terrorist acts in territories of other

States, or from acquiescing in or encouraging activities within

their territories directed towards the commission of such

acts.î120 In doing so, it echoed earlier exhortations in the 1970

Friendly Relations Declaration121 and its 1965 progenitor,

Resolution 2131 (1965).122 Similar prohibitions can be found

in Article 2(4) of the International Law Commissionís 1954

Draft Code of Offenses against the Peace and Security of

Mankind.123

Case law supports these declarations. Most notably, in the

Corfu Channel case the International Court of Justice held that

ì. . . every State has an obligation to not knowingly allow its

territory to be used in a manner contrary to the rights of other

States.î124 Corfu Channel involved an incident in which two

Michael N. Schmitt

42
British destroyers struck mines in Albanian waters while

transiting the Corfu Strait in 1946. Though the evidence was

insufficient to demonstrate that the Albanians laid the mines,

the Court nevertheless held that they had the obligation to

notify shipping of the danger posed by the mines. Albaniaís

failure to do so represented an internationally wrongful act

entailing the international responsibility of Albania. Other case

law and arbitral decisions are in accord.125

Applying the Corfu Channel principle to the case of

terrorism, States that permit their territory to be used as a base

of operations for terrorist acts against other countries have

committed an international wrong. There is no question that

Taliban acquiescence in allowing Afghan territory to be used

by Al Qaeda, assuming arguendo that their conduct is

attributable to the ìStateî of Afghanistan,126 created

responsibility under international law for that wrongful act.

Does this responsibility legally justify the October 7 attacks by

the United States and United Kingdom?

Despite occasionally loose discussion of the subject in the

aftermath of 9/11, the existence of State responsibility for an

international wrong does not justify the use of force in

selfñhelp to remedy the wrong. Traditional reparations for an

international wrong come in the form of restitution,

compensation or satisfaction.127 It is also permissible to take

countermeasures in response to an internationally wrongful

act.128 Countermeasures are ìmeasures which would otherwise

be contrary to the international obligations of the injured State

visñ‡ñvis the responsible State if they were not taken by the

former in response to an internationally wrongful act by the

latter in order to procure cessation and reparation.î129 Various

requirements, such as the existence of an ongoing wrong,130

proportionality of the countermeasure to the injury suffered,131

and a call on the State committing the wrong to comply with

its obligations132 apply to the taking of countermeasures.

Counter-Terrorism and the Use of Force in International Law

43
But it is generally agreed that countermeasures employing

armed force are prohibited.133 Article 50 of the Articles on

State Responsibility specifically provides that

ìCountermeasures shall not affect . . . the obligation to refrain

from the threat or use of force as embodied in the Charter of

the United Nations.î134 This provision tracks the holding in

Corfu Channel. There the International Court of Justice held

that Albaniaís failure to comply with its responsibility did not

justify the British minesweeping of the Strait, an act that

therefore constituted a violation of Albanian sovereignty.

Thus, breach of the obligation not to allow Afghanistan to be

used as a base for terrorist activities did not, alone, justify use

of force against the Taliban.

An identical analysis would apply in assessing whether the

actions of Al Qaeda in conducting the 9/11 (and other) attacks

can be attributed to the Taliban under the law of State

responsibility. The International Law Commissionís Articles

on State Responsibility set forth the standards for imputing an

armed groupís acts to a State for the purpose of assessing State

responsibility. Two are relevant here.

Article 8 provides that the ìconduct of a person or group

shall be considered an act of a State under international law if

the person or group of persons is in fact acting on the

instructions of, or under the direction or control of, that State

in carrying out the conduct.î135 This was the issue in the

Nicaragua case, where Nicaragua argued that the United

States was responsible under international law for violations of

humanitarian law committed by the Contras, the

antiñSandinista rebel group it supported. After finding that the

United States had provided ìsubsidies and other support,î the

Court held that: 

The Court has taken the view that United States

participation, even if preponderant or decisive

Michael N. Schmitt

44
in the financing, organizing, training, supplying

and equipping of the contras, the selection of its

military or paramilitary targets, and the

planning of the whole of its operation, is still

insufficient in itself, . . . for the purpose of

attributing to the United States the acts

committed by the contras in the course of their

military or paramilitary operations in

Nicaragua. All the forms of United States

participation mentioned above, and even the

general control by the respondent State over a

force with a high degree of dependency on it,

would not in themselves mean, without further

evidence, that the United States directed or

enforced the perpetration of the acts contrary to

human rights and humanitarian law alleged by

the applicant State . . . . For this conduct to give

rise to legal responsibility of the United States,

it would in principle have to be proved that that

State had effective control of the military or

paramilitary operations in the course of which

the alleged violations were committed.136

Aside from the Contras, certain individuals, not of US

nationality, were paid by the United States and directly

instructed and supervised by US military and intelligence

personnel. For instance, they carried out such operations as

mining Nicaraguan ports. The Court easily found their actions

imputable to the United States, either because they were paid

and instructed by the United States, and were therefore agents

thereof, or because US personnel had ìparticipated in the

planning, direction, support and executionî of particular

operations.137

The evidence released to date regarding Taliban ties to Al

Qaeda does not suggest that Al Qaeda was under the direction

Counter-Terrorism and the Use of Force in International Law

45
or control of the Taliban in conducting the 9/11 attacks or any

other acts of international terrorism. In fact, some have

suggested precisely the opposite ó that it was the Taliban that

was dependent on Al Qaeda, both financially and militarily.

While that may be a more accurate characterization, such

dependency bears little direct connection to Al Qaedaís

international terrorist campaign.

Article 11 sets forth a second possibly relevant standard. It

provides that ì[c]onduct which is not attributable to a State

under the preceding articles shall nevertheless be considered

an act of that State under international law if and to the extent

that the State acknowledges and adopts the conduct as its

own.î138 This principle lay at the core of the International

Court of Justiceís Diplomatic and

Consular Staff case.139 There the

Court held that the Iranian

government violated its

responsibility to prevent the 1979

seizure by militant students of the

US Embassy in Teheran and

subsequently failed to meet its

obligation to act promptly in ending

the seizure.140 Following the

takeover, the Iranian government,

including its leader, the Ayatollah

Khomeni, expressed approval of the student actions. Indeed, in

a decree issued within two weeks of the seizure, Khomeni

declared that ìthe hostages would remain as they were until the

U.S. had handed over the former Shah for trialî and that ìthe

noble Iranian nation will not give permission for the release . . .

until the American Government acts according to the wish of

the nation.î141 For the International Court of Justice, ì[t]he

approval given . . . by the Ayatollah Khomeni and other organs

of the Iranian State, and the decision to perpetuate them,

translated continuing occupation of the Embassy and detention

Michael N. Schmitt

46

Difficult question:

Was the Taliban

relationship with 

Al Qaeda such that

the terrorist acts

constructively

amounted to a

Taliban armed

attack?
of the hostages into acts of that State.î142 Therefore, while the

Iranian government breached its own obligations when the

Embassy was taken, it became responsible for the seizure itself

(or at least the continuing occupation thereof) when it

supported the student actions and took steps to continue the

occupation.

Are the Taliban responsible for the 9/11 attacks under the

principle of attribution of State responsibility? The level of

Taliban support falls far below that of the Iranian government

in the Embassy case. It did not express open and public

support for the attacks, nor did it ever assume control of the

terrorist campaign in the way that the Iranian government took

control over release of the US hostages. Further, although its

military did conduct combat operations against US and

coalition forces in concert with Al Qaeda, that was only after

October 7, following air attacks on its own facilities and

personnel.

By either of these two standards of State responsibility, it is

difficult to attribute Al Qaedaís terrorist attacks to the Taliban.

That said, any such assessment is factñdependent;

unfortunately, many of the relevant facts tying the Taliban to

Al Qaeda and vice versa remain either unreleased or as yet

undiscovered. However, what must be remembered in

discussions over the State responsibility of the Taliban is that

the existence of responsibility in the general sense is a question

quite distinct from that of whether an armed attack has been

committed by that State, so as to justify selfñdefense by the

State attacked. This is a very fine point. The principles of State

responsibility determine when a State may be held responsible

for an act and thus subject to reparations or countermeasures.

But as noted, forcible countermeasures are not an acceptable

remedy for violations of State responsibility. That is so

whether the issue is harboring a terrorist group or being

responsible for an act committed by one.

Counter-Terrorism and the Use of Force in International Law

47
Nevertheless, certain acts that generate State responsibility

may at the same time justify a violent response. Although

forcible countermeasures are impermissible to make whole the

victim or cause the wrongdoer to desist in breaching an

international obligation, the application of force against the

wrongdoer may be justified as an act of selfñdefense in the

face of an imminent or ongoing armed attack.143 Restated in

the context of the present case, the proper query in assessing

the lawfulness of attacking the Taliban on October 7 is not

whether the Taliban are in any way responsible under

principles of State responsibility for the acts of 9/11. Rather, it

is whether or not the Taliban can be determined to have

committed the armed attack under the law of selfñdefense.

SelfñDefense. No evidence has been released to suggest that

Taliban forces played a direct role in the attacks of 9/11 or any

other Al Qaeda operation. Was the Taliban relationship with Al

Qaeda nevertheless such that the terrorist acts constructively

amounted to a Taliban armed attack?

The precise degree of association between a nonñState

organization and State sponsor necessary for attribution of an

armed attack to the State is a matter of some controversy.144

However, on September 11, the most widely accepted legal

standard on the issue was that set forth in the Nicaragua case.

That case was discussed earlier visñ‡ñvis the nature of an

armed attack, as well as State responsibility. However, the

International Court of Justice also addressed the issue of

imputing an armed attack to a State.

In the case, the United States argued that Nicaragua had

conducted an armed attack against El Salvador through

support to guerillas attempting to overthrow the El Salvadoran

government. This being so, US activities directed against

Nicaragua were, so the argument went, legitimate exercises of

the right of collective selfñdefense with El Salvador. The

Michael N. Schmitt

48
Court rejected the assertion, setting a high standard for

attributing the actions of a nonñState actor to a State in the

context of an armed attack.

There appears now to be general agreement on

the nature of the acts which can be treated as

constituting armed attacks. In particular, it may

be considered to be agreed that an armed attack

must be understood as including not merely

action by regular armed forces across an

international border, but also ìthe sending by or

on behalf of a State of armed bands, groups,

irregulars or mercenaries, which carry out acts

of armed force against another State of such

gravity as to amount toî (inter alia) an actual

armed attack conducted by regular forces, ìor

its substantial involvement thereinî. This

description, contained in Article 3, paragraph

(g), of the Definition of Aggression annexed to

General Assembly resolution 3314(XXIX),

may be taken to reflect customary international

law. 

By this standard, the State to which the acts are to be

attributed must be ìsubstantially involvedî in an operation that

is so grave it would amount to an armed attack if carried out

by regular members of its armed forces. Recall from the earlier

discussion of the holding that armed attacks are measured in

terms of their scale and effects, and that the Court specifically

held that the provision of ìweapons or logistical or other

supportî was insufficient. Further, to constitute an armed

attack by the State, that State must have ìsentî the group into

action or it must be acting on the Stateís behalf. These criteria

resemble the requirement under State responsibility that the

group in question act on the instructions of, or under the

direction or control of, the State to which responsibility is to be

Counter-Terrorism and the Use of Force in International Law

49
imputed. In this sense, the principles of State responsibility can

assist in determining whether specific conduct is an armed

attack. 

It should be noted that the Court was not unanimous in its

findings. Most notably, Judge Stephen Schwebel of the United

States dissented, arguing that there had been an armed attack:

The delictual acts of the Nicaraguan

government have not been confined to

provision of very large quantities of arms,

munitions and supplies (an act which of itself

might be viewed as not tantamount to an armed

attack); Nicaragua (and Cuba) have joined with

the Salvadoran rebels in the organization,

planning and training for their acts of insurgency;

and Nicaragua has provided the Salvadoran

insurgents with commandñandñcontrol

facilities, bases, communications and

sanctuary, which have enabled the leadership of

the Salvadoran insurgency to operate from

Nicaraguan territory. Under both customary

and conventional international law, that scale of

Nicaraguan subversive activity not only

constitutes unlawful intervention in the affairs

of El Salvador; it is cumulatively tantamount to

an armed attack upon El Salvador.145

What seems to run through both the Courtís and Judge

Schwebelís position is that the State must at least exercise

significant, perhaps determinative, influence over the groupís

decisionñmaking, as well as play a meaningful role in the

specific operations at hand, before an armed attack will be

imputed to it. The facts asserted by Judge Schwebel suggest

that Nicaragua not only provided the means to conduct

operations against El Salvador, but it did so in a manner that

Michael N. Schmitt

50
would allow operations it helped plan to be mounted. Further,

by organizing and planning the actions, Nicaragua occupied a

central position in the decisionñmaking hierarchy. By contrast,

the Court focused almost exclusively, as it did regarding the

issue of State responsibility, on the extent of control the State

has over the specific actions of the group. 

There seems to be little evidence that the Taliban ìsentî Al

Qaeda against any particular targets or even that they provided

the materiel and logistic support that the Nicaragua Court

found insufficient to amount to an armed attack. In essence,

the key contribution made by the Taliban was granting Al

Qaeda a relatively secure base of operations. By the classic

Nicaragua test, or even the lower standard advocated by Judge

Schwebel, it would be difficult to argue that the Taliban,

through complicity with Al Qaeda, launched an armed attack

against the United States or any other country. Harboring

terrorists is simply insufficient for attribution of an armed

attack to the harboring State. Rather, the situation appears to

have been a marriage of convenience ó convenient for Al

Qaedaís conduct of external terrorist acts and convenient for

the Talibanís control over territory within Afghanistan and

their battles with internal enemies. 

One further judgment of relevance is that rendered by the

Appeals Chamber of the International Criminal Tribunal for

the Former Yugoslavia in Prosecutor v. Tadic. There the issue

was whether acts of Bosnian Serb forces could be attributed to

Yugoslavia. The Chamber held that the degree of control

necessary for attribution would vary according to the factual

circumstances of the case. Refusing to apply the Nicaragua

approach in its entirety, the Chamber adopted a standard of

ìoverall control going beyond the mere financing and

equipping of such forces and involving also participation in

the planning and supervision of military operationsî for acts

by an ìorganized and hierarchically structured group.î146 It felt

Counter-Terrorism and the Use of Force in International Law

51
the dual requirements of effective control of the group and the

exercise of control over a specific operation were excessive,

except in the cases of individuals acting alone or disorganized

groups.

By way of caveat, it must be noted that Tadic involved

neither State responsibility nor the criteria for attribution of an

armed attack. Rather, the issue was whether the Bosnian Serb

actions could be attributed to Yugoslavia such that there was

an international armed conflict. The existence of such a

conflict was a prerequisite for applicability of various aspects

of humanitarian law to the defendants before the tribunal.

Because there was no jurisprudence on the issue, the Chamber

turned to the law of State responsibility by way of analogy.

Again, and though the opinion is only relevant by analogy to

the issue at hand, it would appear that Taliban relations with Al

Qaeda did not rise to this level. Thus, Al Qaeda actions do not

appear imputable to the Taliban as a matter of State

responsibility, as an armed attack or in the context of having

caused an international armed conflict (although no doubt

exists that its harboring of the terrorists was an internationally

wrongful act). It must be emphasized, however, that this

assessment is entirely factñdependent, and that there is a

relative paucity of reliable openñsource information on the

subject.

To summarize, Al Qaeda conducted an armed attack against

the United States on September 11. That attack activated the

right of selfñdefense, one that continues as long as the terrorist

campaign against the United States can reasonably be

characterized as ongoing. Once attacked, the United States

properly demanded that the Taliban turn over Al Qaeda leaders

and allow the United States to verify that no further operations

were ongoing from the country. When the Taliban failed to

comply, the United States and its partners acquired the right to

Michael N. Schmitt

52
enter Afghanistan for the limited purpose of putting an end to

Al Qaeda operations. Had they done so, and had the Taliban

interfered, the interference would have amounted to a separate

armed attack by the Taliban justifying a response in

selfñdefense by forces conducting the counterñterrorist

campaign. Of course, these arenít the facts; the Taliban only

used force after being directly subjected to attacks by the United

States and its partners because Taliban assets were struck in the

first wave of attacks on October 7. Moreover, from the evidence

available, it does not appear that the Taliban were sufficiently

entwined with Al Qaeda terrorist operations for the 9/11 attacks

to be imputed to it, thereby justifying the immediate use of force

against the Taliban. Were the attacks against the Taliban

therefore illegal? That is a very uncertain matter.

The Evolving Standard of SelfñDefense

There is little doubt that the response to the tragic events of

September 11 has tested accepted understandings of the

international law regarding the use of force. Many would

dispute certain of the legal conclusions set forth above ó that

a terrorist group can mount an ìarmed attackî; that a series of

terrorist attacks can be treated as a single ongoing attack; or

that the United States and the United Kingdom were justified

in forcibly crossing into Afghan territory on October 7. Indeed,

this article has concluded that use of force directly against the

Taliban is difficult to fit within traditional understandings of

attribution of an armed attack.

Such unease has led some to pronounce the traditional

normative system dead in fact, if not in law. For instance,

Michael Glennon has opined that:

the rules concerning the use of force are no

longer regarded as obligatory by states.

Between 1945 and 1999, twoñthirds of the

Counter-Terrorism and the Use of Force in International Law

53
members of the United Nations ó 126 states

out of 189 ó fought 291 interstate conflicts in

which over 22 million people were killed. This

series of conflicts was capped by the Kosovo

campaign in which nineteen NATO

democracies representing 780 million people

flagrantly violated the Charter. The

international system has come to subsist in a

parallel universe of two systems, one de jure,

the other de facto. The de jure system consists

of illusory rules that would govern the use of

force among states in a platonic world of forms,

a world that does not exist. The de facto system

consists of actual state practice in a real world,

a world in which states weigh costs against

benefits in regular disregard of the rules

solemnly proclaimed in the allñbutñignored de

jure system. The decaying de jure catechism is

overly schematized and scholastic,

disconnected from state behavior, and

unrealistic in its aspirations for state conduct.

The upshot is that the Charterís useñofñforce

regime has all but collapsed . . . I suggest that

Article 51, as authoritatively interpreted by the

International Court of Justice, cannot guide

responsible U.S. policyñmakers in the U.S. war

against terrorism in Afghanistan or

elsewhere.147

Professor Glennonís thoughtful analysis exaggerates the de

jureñdeñfacto divide. In fact, what has been happening over

the past halfñcentury is a regular evolution in the global

communityís understanding of the use of force regime. This

evolution has been, as it always is and always must be,

responsive to the changing circumstances in which

Michael N. Schmitt

54
international law operates. Practice does not contradict law so

much as it informs law as to the global communityís normative

expectations. It is a phenomenon that is particularly important

in international law because of the absence of highly

developed constitutive entities and processes.

Consider the changing context in which use of force norms

have operated. In the immediate aftermath of the Second

World War an understandable preference for collective

remedies to threats to international peace and security,

remedies that would be executed through inclusive

international institutions, emerged ó hence the United

Nations and its restrictive use of force regime. With the

outbreak of the Cold War, and its resulting bipolarity, that

system fell into disuse as the veto power of the five permanent

members (Pñ5) rendered the Security Council impotent. States

were therefore compelled to engage in various forms of

coercive selfñhelp to perform tasks that would otherwise have

been the preferred prerogative of the Council.148

The demise of the Cold War removed two contextually

determined constraining influences on the use of force. First,

the Security Council was reinvigorated because the zeroñsum

paradigm of the Cold War no longer held; for the first time in

nearly 50 years, the Pñ5 could share common cause (or at least

not find themselves inevitably in opposition). This meant that

the Council could assume its intended role in the maintenance

of international peace and security. The Council promptly did

so, authorizing one major international effort to counter

aggression, the 1990ñ91 Gulf War, and multiple peace

enforcement operations.

Second, the Cold War had imposed an implicit limitation on

unilateral uses of force ó that they not threaten the fragile

peace between East and West. Thus, for example, whereas

intervention was deemed inappropriate as a general matter

Counter-Terrorism and the Use of Force in International Law

55
during the Cold War (it risked sparking a broader conflict),

intervention within a zone of influence appeared more

palatable (or as ìthe other fellowís businessî). With this

second constraint removed, States today are more willing to

accept unilateral uses of force, as there is less chance of

spillover effects. Witness Operation Allied Force. 

What happened is that the operational code regarding the

use of force shifted with the emergence of new geoñpolitical

circumstances. Circumstances

determine the viability of normative

strategies for advancing shared

community values.149 It is not that

new law emerges or that old law

fades away, as much as it is that the

understanding of the precise

parameters of the law evolves as it

responds to fresh challenges or

leverages new opportunities. That

international law is understood in light of the circumstances in

which it finds itself is a strength, not a weakness.

This is certainly true regarding responses to terrorism.

During much of the Cold War, the pressing problem of

violence outside the classic StateñonñState paradigm was

guerilla warfare by insurgents against a government. Both

sides had their clients, whether States or rebel groups, and in

many cases the conflicts were proxy in nature. The

geopolitical and normative appeal of proxy wars was that they

tended to facilitate avoidance of a direct superpower clash.

Thus, as demonstrated in Nicaragua, a very high threshold

was set for attributing rebel acts to their State sponsors or for

characterizing assistance to a rebel group as an ìarmed attackî

legitimizing a victim Stateís forceful response. This was a very

practical approach. The bipolar superpowers were surely going

to engage in such activity regardless of the normative limits

Michael N. Schmitt

56

It is not that new

law emerges or

that old law fades

away; it is that the

law evolves as it

responds to

changing global

realities
thereon, so a legal scheme that avoided justifying a forceful

response by the other side contributed to the shared

community value of minimizing higher order violence. The

result was creation of a legal fiction that States that were

clearly party to a conflict . . . werenít.

To some extent, this paradigm was illustrated by community

reactions to counterñterrorist operations. Consider Operation

El Dorado Canyon, the 1986 air strikes against terrorist and

Libyan government facilities by US forces in response to the

bombing of the La Belle discothËque in Berlin. The Libyan

leader, Muammar el Qadhafi, had previously praised terrorist

actions. Moreover, in advance of the attacks the United States

intercepted communications to the Libyan Peopleís Bureau in

West Berlin containing an order to attack Americans.

Additional intercepts immediately preceding and following the

La Belle bombing provided further evidence of Libyan

complicity.150

Despite Libyaís support of terrorism, international reaction

to the US operation, which was justified on the basis of

selfñdefense, was overwhelmingly negative.151 Many of the

United Statesí closest allies were critical, with the exceptions

of the United Kingdom and Israel. The General Assembly

passed a resolution condemning the action, while

SecretaryñGeneral Javier Perez de Cuellar issued a statement

ìdeploringî the ìmilitary action by one member state against

another.î152 Viewed in the thenñexisting international security

context, this was an unsurprising reaction. If State sponsorship

of terrorism (a particularly illñdefined term given the

bipolarity of the period) rose to the level of an armed attack

justifying a forceful response in selfñdefense, then, given both

sidesí propensity to support opponents of their foe, the risk of

a superpower affray grew.

Counter-Terrorism and the Use of Force in International Law

57
However, the geopolitical context has changed dramatically

in the last decade. Today there is but one superpower.

Additionally, that antagonism which exists between it and

other significant world players, such as Russia and China, is

unlikely to erupt into open conflict. On the contrary, in many

cases the former antagonists are cooperating against common

threats, a trend illustrated by the recent creation of the

NATOñRussia Council.153

Yet, as the likelihood of interñState conflict receded, the

relative importance of the terrorist threat grew

correspondingly. For the major players on the world scene, it

was no longer attack by another State that dominated strategic

risk assessment, but rather the spread of instability,

particularly through the mechanism of nonñinternational

armed conflict, and the related menace of terrorism, either

domestic or international. Not surprising, normative

understandings shifted accordingly.

That shift was dramatically illustrated by the deafening

silence, described at the outset of this article, over the issue of

the lawfulness of the US and UK attacks of October 7. Of

course, some academic voices pointed to the normative

faultlines in the operations, but academe was by no means

united on the subject. Media criticism was rare, as was that by

important nonñgovernmental organizations. Most

significantly, there was almost no State censure of the actions;

on the contrary, States scrambled to join the cause. 

This reaction was a logical continuation of a trend evident in

two earlier postñCold War responses to terrorism. In 1993, a

plot to assassinate former President George Bush during a visit

to Kuwait was foiled. Investigation suggested Iraqi

government involvement. In response, the United States

launched cruise missiles against Iraqi intelligence facilities.

President Clinton justified the action in the following terms:

Michael N. Schmitt

58
This Thursday, Attorney General Reno and

Director of Central Intelligence Woolsey gave

me their findings. Based on their investigation

there is compelling evidence that there was, in

fact, a plot to assassinate former President Bush

and that this plot, which included the use of a

powerful bomb made in Iraq, was directed and

pursued by the Iraqi intelligence service.

These actions were directed against the Iraqi

Government, which was responsible for the

assassination plot. Saddam Hussein has

demonstrated repeatedly that he will resort to

terrorism or aggression if left unchecked. Our

intent was to target Iraqís capacity to support

violence against the United States and other

nations and to deter Saddam Hussein from

supporting such outlaw behavior in the future.

Therefore, we directed our action against the

facility associated with Iraqís support of

terrorism, while making every effort to

minimize the loss of innocent life.154

Of course, Iraq is a unique case given that an international

armed conflict with the United States had occurred in 1991

(and arguably continues today). Nevertheless, the international

community generally supported the strikes, or at least muted

its criticism thereof. Of the Pñ5, only China expressed

concern. By contrast, support was voiced by, inter alia, the

United Kingdom, Israel, Russia, Germany, Italy, Japan and

South Korea, as well as the three Islamic States then sitting on

the Security Council, Pakistan, Djibouti and Morocco. Egypt,

Jordan and Iran criticized the attack, but on the basis of the

civilian casualties caused.155

Counter-Terrorism and the Use of Force in International Law

59
What is normatively remarkable is that the attack was

somewhat questionable as a traditional exercise of

selfñdefense, the legal basis asserted by the United States. It

was in response to a plot that had already been foiled; indeed,

some of those directly responsible for executing it were behind

bars. Additionally, there was no assertion that this was but one

phase in a continuing campaign by the Iraqis against the

United States. Interestingly, the Security Council appeared

more interested in the facts of the case, which it reportedly

found sufficient to establish Iraqi involvement, than in the

legal sufficiency of the US actions.156

A more viable argument legally would have been that an

international armed conflict was still in existence between the

United States and Iraq, punctuated only by a ceaseñfire

agreement, the terms of which had been breached by Iraqi

complicity in the plot. Curiously, that argument never

surfaced. Instead, Article 51 was the sole legal justification

asserted, an assertion that was relatively uncontested. It is also

important to note that, aside from the strict legal stylization,

the strikes were characterized as deterrent in purpose, a

warning to Iraq to desist from any further involvement in acts

of terrorism. This purpose has pervaded virtually every

justification for striking back at terrorists over the past two

decades.

The relative lack of criticism is all the more striking when

contrasted with that generated by the 1986 attacks against

Libya. Some 50 Americans were injured and two died in the

La Belle Disco attacks. Further, prior to the attacks Qadhafi

had threatened that the Libyans were ìcapable of exporting

terrorism to the heart of America,î a threat repeated on

multiple occasions.157 There was no reason at the time to

believe the Libyans would desist in their support of terrorism

against the United States; indeed, such support continued after

the strikes, most notably with the bombing of Pan Am 103

Michael N. Schmitt

60
over Lockerbie.158 Thus, the severity of the terrorist attack and

the likelihood more were forthcoming made the Libya case

more egregious than the plot against George Bush.

Nevertheless, international reaction differed dramatically.

Further evidence of the trend came in 1998 in response to

the bombings of the US embassies in Nairobi and Dar es

Salaam. Almost 300 people, including 12 Americans, perished

in the attacks, which were tied to Usama bin Laden and Al

Qaeda. In response, the United States launched cruise missile

attacks against terrorist training camps in Afghanistan and a

pharmaceutical plant suspected of involvement in chemical

weapons production in Sudan. On the day they were

conducted, President Clinton announced his rationale for

ordering the attacks:

First, because we have convincing evidence

these groups played the key role in the

Embassy bombings in Kenya and Tanzania;

second, because these groups have executed

terrorist attacks against Americans in the past;

third, because we have compelling information

that they were planning additional terrorist

attacks against our citizens and others with the

inevitable collateral casualties we saw so

tragically in Africa; and fourth, because they

are seeking to acquire chemical weapons and

other dangerous weapons.159

Formal legal justification for the actions came in the

required notification of the Security Council that actions in

selfñdefense had been taken.

These attacks were carried out only after

repeated efforts to convince the Government of

the Sudan and the Taliban regime in

Counter-Terrorism and the Use of Force in International Law

61
Afghanistan to shut these terrorist activities

down and to cease their cooperation with the

bin Laden organization. That organization has

issued a series of blatant warnings that ìstrikes

will continue from everywhereî against

American targets, and we have convincing

evidence that further such attacks were in

preparation from these same terrorist facilities.

The United States, therefore, had no choice but

to use armed force to prevent these attacks from

continuing. In doing so, the United States has

acted pursuant to the right of self defence

confirmed by Article 51 of the Charter of the

United Nations. The targets struck, and the

timing and method of attack used, were

carefully designed to minimize risks of

collateral damage to civilians and to comply

with international law, including the rules of

necessity and proportionality.160

International reaction to the two strikes was telling.

Although Iran, Iraq, Libya, Pakistan,161 Russia and Yemen

condemned them, Australia, France, Germany, Japan, Spain

and the United Kingdom were supportive.162 In other words,

support or condemnation tended to track political alignment

with the United States. More normatively significant is the

difference in the reaction to the two strikes. The League of

Arab Statesí Secretariat condemned the strikes against the

Sudanese pharmaceutical factory, but not those against the

terrorist bases in Afghanistan.163 Similarly, Sudan, the Group

of African States, the Group of Islamic States and the League

of Arab States individually asked the Security Council to

consider the attacks against the pharmaceutical plant and send

a factñfinding mission to Sudan, but did not do likewise

visñ‡ñvis the strikes into Afghanistan.164

Michael N. Schmitt

62
The best explanation for the difference is revealed in the

brouhaha that followed the strikes on the Sudanese factory.

Almost immediately questions began to surface in the press

regarding the accuracy of US claims that the plant was tied to

chemical weapon production. In the end, the United States

never made a convincing case that the plant was engaged in the

activities alleged.165 Moreover, even if the assertions had been

accurate, the causal relationship between the plant and the

attacks against the embassies was indirect at best. By contrast,

little doubt existed that terrorists were operating from bases in

Afghanistan with the seeming acquiescence of the Taliban or

that the organization targeted was tied to the bombings. 

The reaction of the politically relevant actors such as States,

NGOs and the media in this case reflects a general sense that

it was not the fact that the United States struck back which

caused concern as much as it was that the United States ìgot it

wrongî in the Sudanese case. In other words, if a State is going

to take the dramatic step of conducting military operations

against terrorists, it needs to have sufficient evidence of the

connection between the target and the act that was committed,

as well as a reasonable belief that future acts are on the

horizon. 

What is the relationship between these incidents and the law

of selfñdefense as it applies to international terrorism? As

Professor Reisman has perceptively noted, ìlaw is not to be

found exclusively in formal rules but in the shared

expectations of politically relevant actors about what is

substantively and procedurally right.î166 Though such New

Haven School pronouncements often evoke controversy, there

can be little doubt that the received law ó customary,

conventional and case law ó is informed by State practice and

the practice of other politically relevant actors on the

international scene. Their normative expectations as to how

law should foster shared community values are determinative

Counter-Terrorism and the Use of Force in International Law

63
of international lawís vector. In the context of counterñterrorist

operations conducted in selfñdefense, a number of conclusions

as to possible criteria bearing on the international communityís

assessment of lawfulness can be suggested from both the legal

analysis offered earlier and the short discussion of the evolving

international reaction to counterñterrorist operations.

Armed Attack. A community consensus now appears to

exist that armed attacks may be conducted by terrorist

organizations. At the same time, such attacks constitute

violations of international and domestic criminal law. Thus,

the target State may respond to them with armed force in

selfñdefense and/or engage in law enforcement activities. To

amount to an armed attack, the ìscale and effectsî must be

ìsignificant,î although in a series of related attacks

significance is a cumulative calculation. This is a somewhat

ambiguous standard, but factors such as the nature and

capabilities of the organization conducting the attack, the

extent of human injury and physical damage caused (or likely

to have been caused if the attack is foiled or otherwise

unsuccessful), the relation of the attack to previous attacks and

the method and means used to conduct it bear on the appraisal.

Necessity. For compliance with the necessity requirement of

selfñdefense, there must be a sound basis for believing that

further attacks will be mounted and that the use of armed force

is needed to counter them. This requires the absence of a

reliable means other than force to counter the prospective

attacks. The relative success of any law enforcement efforts (or

likelihood thereof) will affect the extent to which resort to

armed force is necessary. Similarly, if selfñdefense operations

involve crossing into another Stateís territory, that State must

be unable or unwilling to prevent the terrorists from

continuing to threaten the victim State.

Michael N. Schmitt

64
As an aside, the option of seeking Security Council action

under Chapter VII has no relation to the necessity assessment.

Although it is sometimes asserted that States should turn to the

Council for assistance if the opportunity presents itself, Article

51 contains no such legal obligation.

Proportionality. Selfñdefense operations against terrorists

and States involved in terrorism are

limited to the nature, targets, level

of violence and location required to

defeat an ongoing attack or, if that

attack has ended, prevent any

further reasonably foreseeable

attacks. That said, those who act in

selfñdefense should be sensitive to

the other face of proportionality, its

jus in bello face.

Imminency. Selfñdefense may only be conducted against an

attack that is imminent or ongoing. An attack is imminent

when the potential victim must immediately act to defend

itself and the potential aggressor has irrevocably committed

itself to attack. In the context of

terrorism, this point may occur well

before the planned attack due to the

difficulty of locating and tracking

terrorists. Imminency is not

measured by the objective time

differential between the act of

selfñdefense and the attack it is

meant to prevent, but instead by the extent to which the

selfñdefense occurred during the last window of opportunity. 

More significant are responses to ongoing attacks. The

acceptability of viewing separate acts of terrorism conducted

by the same organization (or closely related organizations

Counter-Terrorism and the Use of Force in International Law

65

Self-defense

against terrorism is

limited to the

nature, targets,

level of violence,

and location

required to defeat it

An attack is

imminent when the

potential victim

must act

immediately to

defend itself
acting in concert) as a single ongoing attack appears clear in

the aftermath of the response to 9/11. Thus, whereas Operation

El Dorado Canyon was widely characterized as punitive in

nature, the US counterñterrorist strikes in 1993, 1998 and 2001

were generally seen as appropriately preventive. In other

words, the understanding of armed attack has evolved from

one looking at particular operations in isolation, and asking

whether each is imminent or ongoing in and of itself, to one

where terrorists are viewed as conducting campaigns. Once it

is established that an ongoing campaign is underway, acts of

selfñdefense are acceptable throughout its course, so long as

the purpose is actually to defeat the campaign. In this sense,

deterrent selfñdefense has become, or is at least in the process

of becoming, accepted. As noted, almost all justifications,

official and otherwise, of counterñterrorist strikes cite the

purpose of preventing and deterring future terrorism.

Purpose. The sole acceptable purpose for selfñdefense

operations is to defeat an ongoing attack or prevent one that is

imminent. The motivation cannot be retribution, general

deterrence (deterring terrorism generally vice deterring

specific acts and actors), punishment or any other motive. Of

course, although each of these may be the logical consequence

of a defensive action or, perhaps, a secondary goal, they are

impermissible as the primary purpose of the actions.

Conducting SelfñDefense in Another State. It is

permissible to cross into the territory of another State to

conduct defensive counterñterrorist operations when that State

has granted consent to do so or when it is unable or unwilling

to effectively prevent terrorist activities on its soil. In the latter

two cases, a request from the victim State to take the steps that

are necessary must precede nonconsensual entry into the

country. Operations may only be conducted against the

terrorists and their assets; however, if the host State forcibly

interferes with them, then that State may have committed an

Michael N. Schmitt

66
armed attack against the force carrying out the

counterñterrorist actions.

Conducting SelfñDefense Against a State Sponsor. The

formal rules regarding the extent of

support to a terrorist organization

necessary to attribute an armed

attack to a State appear to differ

from the normative expectations of

the global community. Those rules

require a high degree of control

over a specific operation, such that

the terrorist organization is sent by

or on behalf of a State to conduct

the attack. Mere harboring does not suffice.

However, normative expectations are clearly in the process

of rapid evolution. Seemingly authoritative articulations of the

standard, such as that by the International Court of Justice in

Nicaragua, are increasingly out of step with the times.

Although no definitive conclusions can be drawn yet regarding

the extent and nature of relationship between the State and

terrorist group deemed sufficient to impute an armed attack,

several factors seem to have informed the communityís

general support (or at least lack of criticism) for the strikes

against the Taliban. Of particular importance is the fact that the

Security Council had made repeated demands that the Taliban

put an end to the use of its territory by terrorists, all to no avail.

The existence of these warnings by an authoritative

international body rendered the Taliban the masters of their

own fate. Refusal to cooperate even after the unthinkable

happened on September 11, despite demands and an

opportunity to do so, only served to exacerbate their culpability.

Moreover, the terrorists being harbored were of a

particularly nasty sort. They had conducted multiple

Counter-Terrorism and the Use of Force in International Law

67

Formal rules and

normative

expectations differ

when it comes to

determining

whether a State has

supported terrorist

organizations
operations in the past that resulted in hundreds of casualties,

and had now mounted an attack in which the death toll was

measured in the thousands. Their attack also had global

impact; financial reverberations were felt throughout the world

economy, citizens of over 80 countries were killed, and a

pervasive sense of fear infected millions. Clearly, the scale and

effects of Al Qaedaís attacks bore directly on the communityís

assessment of Taliban actions (or the lack thereof).

Additionally, the relationship between Al Qaeda and the

Taliban was extremely close, actually symbiotic in many ways.

Although no evidence has been released of direct complicity in

the 9/11 attacks, it is difficult to imagine a more cooperative

host for Al Qaeda than the Taliban, cooperation that was the

inevitable result of the Talibanís own dependence on Al Qaeda.

Finally, the Taliban were viewed as illegitimate in many

ways. Only three countries ó Saudi Arabia, the United Arab

Emirates and Pakistan ó recognized them as the proper

government of Afghanistan, by no stretch of the term could

they be described as democratic and their human rights record

was horrendous.167 To describe the Taliban as internationally

ostracized would be an understatement. Thus, conducting

assaults against them seemed to do less violence to

countervailing international law principles such as territorial

integrity than would similar actions against other governments

and States.

Drawing these strands together, relevant factors in assessing

the lawfulness of a response against a State sponsor include the

severability (or lack thereof) between it and the terrorist group;

the frequency, source and timing of warnings to desist from

cooperation with the group; the scale and nature of the

cooperation; the extent to which the State is perceived as

generally law abiding and legitimate, or not; the inclusivity of

the threat in terms of States threatened; and the severity of the

Michael N. Schmitt

68
acts committed by the terrorist group which the State has

chosen to associate itself with. Further, it appears that

selfñdefense visñ‡ñvis State involvement (like that against the

terrorists themselves) is heading in deterrent directions.

Although each determination will be factñspecific, it is clear

that the bar is being measurably lowered.

Evidence. As illustrated in the case of the 1998 strikes

against the Sudanese pharmaceutical plant, the international

community expects States carrying out counterñterrorist

strikes to act only on the basis of reliable information. The

United States learned its lesson well; in the recent attacks, the

United States provided briefings on Al Qaeda and Taliban

activities to the Security Council, North Atlantic Council and

other intergovernmental organizations, as well as numerous

States bilaterally.

The incidents considered above highlight the core facts that

need to be demonstrated: that the target of the selfñdefense

operations conducted the attack,

either directly or constructively, and

that the selfñdefense complies with

the requirements of necessity,

proportionality and imminency. A

much more difficult question is that of how heavy the burden

of proof should be.

Because the issue at hand involves the most significant act

of international intercourse, the use of armed force, a high

standard of proof is obviously required. A ìpreponderance of

the evidenceî standard (i.e., evidence that the fact in issue is

more likely than not) is clearly insufficient to justify acts of

such import. On the other hand, a ìbeyond a reasonable doubtî

would prove impractical in all but the rarest of cases. The

shadowy world of international terrorism simply does not lend

itself to immediate access to credible information. By this

Counter-Terrorism and the Use of Force in International Law

69

How heavy 

should the burden

of proof be?
standard, States would almost never have sufficient evidence

to mount a timely and decisive response to a terrorist act.

Mary Ellen OíConnell has suggested a ìclear and

convincingî standard.168 Although acknowledging that no

accepted standard exists, she draws on domestic law

evidentiary standards and an assortment of decisions by

international courts, including the Nicaragua case,169 as well as

the work of other scholars.170 Her suggested standard is

consistent with the US notification of selfñdefense to the

Security Council, in which the United States adopted a ìclear

and compellingî evidentiary standard;171 this was also the

verbiage used to describe the evidence presented to the North

Atlantic Council.172 Application of such a standard, or an

analogous one, meets the dual requirements of practicality and

rigor ó practicality in the sense that an evidentiary burden

should not render a State paralyzed as it seeks the requisite

quality of evidence, but rigor in that the burden should be

heavy enough to preclude States from reacting precipitously to

terrorist attacks. Ultimately, an adequacy assessment will rest

on the international communityís determination of whether a

reasonable international actor would have acted in

selfñdefense on the basis of the evidence in question. All such

assessments are inherently subjective and contextual.

Once a State possesses the requisite evidence, must it

disclose it? Professor Jonathan Charney argues that it must.

To limit the use of force in international

relations, which is the primary goal of the

United Nations Charter, there must be checks

on its use in selfñdefense. Disclosure to the

international community of the basis for such

action would help to serve this purpose. The

alleged credibility of conclusory statements by

a stateís leadership should not be a sufficient

Michael N. Schmitt

70
basis for actions in selfñdefense since it would

encourage abuse. When attacks on a state are so

grave as to justify actions in selfñdefense, the

supporting evidence would normally be readily

available. Disclosure of that evidence should be

required even if the state would wish to claim

that classified information would be disclosed.

The use of force in selfñdefense is limited to

situations where the state is truly required to

defend itself from serious attack. In such

situations, the state must carry the burden of

presenting evidence to support its actions,

normally before these irreversible and

irreparable measures are taken.173

This is a noble proposal, but unfortunately an impractical

one. In the vast majority of cases, the information necessary to

establish the material facts will be extraordinarily sensitive.

Releasing it may endanger the lives of human sources,

jeopardize ongoing intelligence operations of use in targeting

the terrorists or foiling future attacks, surrender the element of

surprise, and reveal critical information regarding the extent to

which the battlefield and the enemyís command and control

are transparent to the State engaged in selfñdefense operations.

An absolute disclosure standard is not one the international

community will ever adopt in the case of selfñdefense against

terrorism.

A more reasonable standard would require disclosure to the

extent practicable in the circumstances. Professor Charneyís

concern about abuse of the right to selfñdefense is well

founded; however, that concern must be balanced against the

need to be able to conduct selfñdefense, and otherwise

safeguard oneself from terrorists, effectively. Moreover, the

situation is not always a strict disclosureñno disclosure

conundrum. For instance, it may serve both purposes to

Counter-Terrorism and the Use of Force in International Law

71
disclose the necessary information in closed session, as was

done when the United States briefed its NATO allies. The

subsequent support of States that have received such briefings

serves as a safeguard against abuse, albeit a less than perfect

one. Additionally, it may be possible to disclose information

after the fact, as was done by the United States in 1997

regarding Operation El Dorado Canyon.174 Doing so will allow

States to build a track record of credibility in their claims, a

particularly valuable safeguard in those cases where

immediate disclosure is impossible.

Conclusion

It has been asked whether the attacks of September 11

ushered in a dramatically new era in

international law. This article has

suggested that in most respects the

law on the use of force has proven

adequate visñ‡ñvis international

terrorism. Where it has not, the

emerging normative expectations

represent less a new era than the

logical and constant evolution of the

existing legal system in the face of

changing global realities. That

evolution has resulted in some

degree of softening in the community understanding of when

selfñdefense is appropriate.

Such a softening is appropriate in the face of the new threat

environment. Terrorism today represents a particularly

pernicious prospect. Unfortunately, the attacks that occurred

last September may represent only the tip of the iceberg.

Thousands of individuals trained under bin Laden are at large

worldwide.175 More ominously, the threat of terrorism using

weapons of mass destruction looms ever larger. The normative

Michael N. Schmitt

72

No definitive

conclusions can be

drawn regarding

attacks against a

State providing

assistance to

terrorists, but

clearly the

threshold is

dropping
system developed for StateñonñState conflict, in which the

risk of super power confrontation was always present, is

predictably shifting to remain responsive to community values

in the face of the changing threat.

Consider the apparent relaxation in the requirements for

attribution of an armed attack. Although it may make striking

at a State in selfñdefense more acceptable, thereby heightening

the likelihood of StateñonñState conflict, it may have just the

opposite effect by serving as an effective deterrent to State

sponsorship without risking the higher order conflict that was

the danger during the Cold War. Similarly, characterizing

terrorist attacks as part of a campaign rather than a series of

individual actions actually gives the State acting in

selfñdefense an opportunity to seek resolution of the situation

without being compelled to immediately resort to force lest the

imminency pass. This permits greater community involvement

in the decision process and greater opportunity to gather and

assess evidence.

So the final normative verdict on the US and coalition

attacks against Al Qaeda and the Taliban is uncertain. The

attacks against Al Qaeda appear novel, but consistent with the

community expectations existing on September 10. By

contrast, the attacks against the Taliban represent a less than

crystalline glimpse of the direction in which the international

law regarding responses to terrorism may be heading. But

given the existing security landscape, the vector appears

positive. 

Counter-Terrorism and the Use of Force in International Law

73
Endnotes

1 For an excellent discussion of how the attacks were a turning point in the

evolution of international terrorism, see Paul J. Smith, Transnational

Terrorism and the al Qaeda Model: Confronting New Realities,

PARAMETERS, Summer 2002, at 33. See also, Michael Howard, Whatís

in a Name? How to Fight Terrorism, FOREIGN AFFAIRS,

January/February 2002, at 8, which argues that declaring a ìwarî on

terrorism was a ìterrible and irrevocable error.î Id. at 8.

2 The extent to which the GWOT represents a fundamental shift in

US strategies for dealing with threats is apparent in President

Bushís discussion of preemptive strategies. See Remarks by the

President at 2002 Graduation Exercise of the United States

Military Academy, June 1, 2002 (visited June 18, 2002)

<http://www.whitehouse.gov/news/releases/2002/06/20020601ñ3.html>.

See The United States National Security Strategy, Sept. 2002,

<http://www.whitehouse.gov/nsc/nss.html>.

3 See Michael J. Glennon, The Fog of Law: SelfñDefense, Inherence, and

Incoherence in Article 51 of the United Nations Charter, 25 HARVARD

JOURNAL OF LAW AND PUBLIC POLICY 539 (2002). 

Id. at 540.

4 See, e.g., Jack M. Beard, Americaís New War on Terror: The Case for

SelfñDefense Under International Law, 25 HARVARD JOURNAL OF

LAW AND PUBLIC POLICY 559 (2002).

[T]he case for Americaís forcible response to the

September 11 attacks as being fully consistent with the

inherent right of selfñdefense under customary

international law and Article 51 of the UN Charter is very

strong. The unanimous condemnation of the attacks by

the UN General Assembly, the affirmation of the right of

selfñdefense by the Security Council, the growing

consensus in the international community to hold states

accountable for terrorist actions, and the repeated

condemnation by the Security Council of the Taliban

Regimeís support of terrorists in particular, clearly help

establish an appropriate framework under international

law for the exercise of selfñdefense by the United States.

Michael N. Schmitt

74
Id. at 589ñ90.

5 That component of international law that governs when it is that a State

may resort to force in pursuit of its national interests, such as defending

itself from armed attack.

6 Pursuant to Article 31 of the Vienna Convention on the Law of Treaties:

1. A treaty shall be interpreted in good faith in

accordance with the ordinary meaning to be given to the

terms of the treaty in their context and in light of its

object and purpose . . . ;

2. There shall be taken into account together with the

context: . . .

b. any subsequent practice in the application of

the treaty which establishes the agreement of

the parties regarding its interpretation . . . .

Vienna Convention on the Law of Treaties, May 23, 1969, art. 31, 1155

UNTS 331, 8 ILM 679 (1969). This point was reiterated by the

International Court of Justice in Competence of the General Assembly for

the Admission of a State to the United Nations. There, the Court noted ìthe

first duty of a tribunal which is called upon to interpret and apply the

provisions of a treaty is to endeavour to give effect to them in their natural

and ordinary meaning in the context in which they occur.î 1950 I.C.J. 4, 8.

7 For background on bin Laden, see PETER L. BERGEN, HOLY WAR,

INC.: INSIDE THE SECRET WORLD OF OSAMA BIN LADEN (2001);

Michael Dobbs, Bin Laden: Architect of New Global Terrorism,

WASHINGTON POST, Sept. 16, 2001, at A8.

8 United Kingdom Press Release, 10 Downing Street Newsroom,

Responsibility for the Terrorist Atrocities in the United States,

Oct. 4, 2001, at paras. 21ñ22 (visited June 18, 2002)

<http://www.numberñ10.gov.uk/news.asp?NewsId=2686>. As to US

confirmation of the facts, see David E. Sanger, White House Approved

Data Blair Released, N.Y. TIMES, Oct. 6, 2001, at B6.

9 Indictment, United States v. Usama bin Laden et al., S(2) 98 Cr. 1023

(LBS) (S.D.N.Y. Nov. 4, 1998). 

10 Department of State, Patterns of Global Terrorism, app. B: Background

Information on Terrorist Groups, Al Qaeda, April 30, 2001 (visited June 18,

2002) <http://www.state.gov/s/ct/rls/pgtrpt/2000/2450.htm>.

Counter-Terrorism and the Use of Force in International Law

75
11 Proclamation No. 7463, 66 Federal Register 48,199 (Sept. 18, 2001). 

12 Exec. Order No. 13,223, 66 Federal Register 48,201 (Sept. 18, 2001). A

number of other steps were taken. For instance, President Bush gave the

Treasury Department greater power to undermine financial support for

terrorism through freezing assets and imposing financial sanctions on those

who refused to cooperate in the effort. Exec. Order No. 13,224, 66 Federal

Register 49,079 (2001).

13 Exec. Order No. 13,228, 66 Federal Register 51,812 (Oct. 10, 2001).

14 Authorization for Use of Military Force, Public Law No. 107ñ40, 115

Stat. 224 (2001).

15 Address Before a Joint Session of the Congress on the United States

Response to the Terrorist Attacks of September 11, 37 WEEKLY

COMPILATION OF PRESIDENTIAL DOCUMENTS 1347, 1347 (Sept.

20, 2001).

16 For background on the Taliban, see AHMED RASHID, TALIBAN:

MILITANT ISLAM, OIL AND FUNDAMENTALISM IN CENTRAL

ASIA (2001); PETER MARSDEN, THE TALIBAN: WAR, RELIGION

AND THE NEW ORDER IN AFGHANISTAN (1998).

17 Address Before a Joint Session of the Congress, see note 15 above.

18 Id.

19 Presidentís Radio Address, 37 WEEKLY COMPILATION OF

PRESIDENTIAL DOCUMENTS 1429, 1430 (Oct. 6, 2001).

20 UN CHARTER, art. 51. Article 51 provides that:

Nothing in the present Charter shall impair the inherent

right of individual or collective selfñdefence if an armed

attack occurs against a Member of the United Nations,

until the Security Council has taken measures necessary

to maintain international peace and security. Measures

taken by Members in the exercise of this right of

selfñdefence shall be immediately reported to the

Security Council and shall not in any way affect the

authority and responsibility of the Security Council

under the present Charter to take at any time such action

as it deems necessary in order to maintain or restore

international peace and security.

21 Letter from the Permanent Representative of the United States of

America to the United Nations Addressed to the President of the Security

Michael N. Schmitt

76
Council (Oct. 7, 2001), UN Doc. S/2001/ (visited June 18, 2002)

<http://www.un.int./usa/sñ2001ñ946.htm> [hereinafter US Letter].

22 Address to the Nation Announcing Strikes Against Al Qaeda Training

Camps and Taliban Military Installations, 37 WEEKLY COMPILATION

OF PRESIDENTIAL DOCUMENTS 1432, 1432 (Oct. 7, 2001).

23 Letter from the Charge díAffaires of the Permanent Mission

of the United Kingdom of Great Britain and Northern Ireland

to the United Nations addressed to the President of the

Security Council (Oct. 7, 2001) (visited June 18, 2002)

<http://www.ukun.org/xq/asp/SarticleType.17/Article_ID.328/qx/articles_

show.htm>.

24 S.C. Res. 1368, pmbl. (Sept. 12, 2001). It is interesting that the Security

Council did not reference selfñdefense in response to the 1998 attacks on

the East African embassies even though the United States formally invoked

Article 51. According to Article 39 of the UN Charter, the Security Council

has cognizance over ìany threat to the peace, breach of the peace, or act of

aggressionî and decides upon measures necessary to ìmaintain or restore

international peace and security.î UN CHARTER, art. 39. Therefore,

labeling the acts as a threat to international peace and security is

normatively significant in that it empowers the Council to act. 

25 S.C. Res. 1373, pmbl. (Sept. 28, 2001).

26 G.A. Res. 56/1 (Sept. 18, 2001).

27 S.C. Res. 1378 (Nov. 14, 2001).

28 S.C. Res. 1386 (Dec. 20, 2001). Pursuant to the Agreement on

Provisional Arrangements in Afghanistan pending the

Reñestablishment of Permanent Government Institutions (Bonn

Agreement of Dec. 5, 2001), ISAF is to assist in maintenance of

security in the vicinity of Kabul. ISAF executed a military technical

agreement (MTA) with the Interim Administration in Afghanistan on

January 4, 2002. For the text of the Bonn Agreement, see

<http://www.uno.de/frieden/afghanistan/talks/agreement.htm>

(visited June 18, 2002). The MTA text is at

<http://www.operations.mod.uk/isafmta.pdf> (visited June 18, 2002).

29 S.C. Res. 1390 (Jan. 20, 2002). The operation itself is described by the

British Ministry of Defence at <http://www.operations.mod.uk/fingal/>

(visited June 18, 2002).

Counter-Terrorism and the Use of Force in International Law

77
30 UN CHARTER, art. 42. The text reads: 

Should the Security Council consider that measures

provided for in Article 41 would be inadequate or have

proved to be inadequate, it may take such action by air,

sea, or land forces as may be necessary to maintain or

restore international peace and security. Such action may

include demonstrations, blockade, and other operations

by air, sea, or land forces of Members of the United

Nations.

31 North Atlantic Treaty Organization (NATO), Press Release No. 124,

Statement by the North Atlantic Council (Sept. 12, 2001) (visited June 18,

2002) <http://www.nato.int/docu/pr/2001/p01ñ124e.htm>.

32

The Parties agree that an armed attack against one or

more of them in Europe or North America shall be

considered an attack against them all and consequently

they agree that, if such an armed attack occurs, each of

them, in exercise of the right of individual or collective

selfñdefence recognised by Article 51 of the Charter of

the United Nations, will assist the Party or Parties so

attacked by taking forthwith, individually and in concert

with the other Parties, such action as it deems necessary,

including the use of armed force, to restore and maintain

the security of the North Atlantic area. 

North Atlantic Treaty, Aug. 24, 1959, art. 5, TIAS 1964, 34 UNTS 243. 

33 Secretary General Lord Robertson, Statement at NATO

Headquarters (Oct. 2, 2001) (visited June 18, 2002)

<http://www.nato.int/docu/speech/2001/s011002a.htmhttp://www.nato.int/

docu/speech/2001/s011002a.htm>.

34 ìThe High Contracting Parties agree that an armed attack by any State

against an American State shall be considered as an attack against all the

American States and, consequently, each one of the said Contracting

Parties undertakes to assist in meeting the attack in the exercise of the

inherent right of individual or collective selfñdefense recognized by Article

51 of the Charter of the United Nations.î InterñAmerican Treaty of

Reciprocal Assistance, Sept. 2, 1947, art. 3.1, 62 Stat. 1681, 21 UNTS 77.

Michael N. Schmitt

78
35 Terrorist Threat to the Americas, Resolution 1, TwentyñFourth Meeting

of Consultation of Ministers of Foreign Affairs Acting as Organ of

Consultation In Application of the InterñAmerican Treaty of Reciprocal

Assistance, OEA/Ser.F/II.24, RC.24/RES.1/01 (Sept. 21, 2001).

36 Prime Minister John Howard, Government Invokes ANZUS Treaty ó

Press Conference (Sept. 14, 2001) (visited June 18, 2002) <

http://australianpolitics.com.au/foreign/anzus/01ñ09ñ14anzusñinvoked.sht

ml>. See also White House, Fact Sheet: Operation Enduring Freedom

Overview (Oct. 1, 2001) (visited June 18, 2002) <

http://www.state.gov/s/ct/rls/fs/2001/5194.htm>. Article VI of the ANZUS

Treaty provides: ìEach Party recognizes that an armed attack in the Pacific

Area on any of the Parties would be dangerous to its own peace and safety

and declares that it would act to meet the common danger in accordance

with its constitutional processes.î Security Treaty (Australia, New Zealand,

United States), Sept. 1, 1951, art. IV, 3 U.S.T. 3420, 3422, 131 U.N.T.S. 83,

84.

37 Fact Sheet, see note 36 above.

38 Sean D. Murphy, Terrorism and the Concept of ìArmed Attackî in

Article 51 of the UN Charter 43 HARVARD INTERNATIONAL LAW

JOURNAL 41, 49 (2002); Sean D. Murphy, Contemporary Practice of the

United States Relating to International Law, 96 AMERICAN JOURNAL

OF INTERNATIONAL LAW 237, 248 (2002).

39 Murphy, Contemporary Practice (2002), see note 38 above, at 248. The

European Council ìconfirm[ed] its staunchest support for the military

operations . . . which are legitimate under the terms of the United Nations

Charter and of Resolution 1368.î Declaration by the Heads of State or

Government of the European Union and the President of the Commission:

Followñup to the September 11 Attacks and the Fight Against Terrorism,

Oct. 19, 2002, SN 4296/2/01 Rev. 2. 

40 Perhaps best illustrative of the coalition nature of the campaign were

operations that month from Manas airport, near Bishkek, Kyrgyz Republic.

Although typically a sleepy airfield, it was hosting US and French fighterñbombers;

Australian and French tankers; transport aircraft from Spain, the

Netherlands, Denmark and Norway; and a South Korean medical team.

Americans in a Strange Land, THE ECONOMIST, May 4, 2002, at 41. 

41 UN CHARTER, art. 2(4). On this article, see Albrecht Randelzhofer,

Article 2, in THE CHARTER OF THE UNITED NATIONS: A

Counter-Terrorism and the Use of Force in International Law

79
COMMENTARY 72 (Bruno Simma ed., 1995).

42 UN CHARTER, art. 42.

43

The Security Council shall, where appropriate, utilize

such regional arrangements or agencies for enforcement

action under its authority. But no enforcement action

shall be taken under regional arrangements or by regional

agencies without the authorization of the Security

Council, with the exception of measures against any

enemy state, as defined in paragraph 2 of this Article,

provided for pursuant to Article 107 or in regional

arrangements directed against renewal of aggressive

policy on the part of any such state, until such time as the

Organization may, on request of the Governments

concerned, be charged with the responsibility for

preventing further aggression by such a state.

UN CHARTER, art. 53.1.

44 On this issue, see Adam Roberts, The SoñCalled ëRightíof Humanitarian

Intervention, 3 YEARBOOK OF INTERNATIONAL HUMANITARIAN

LAW 3 (2000).

45 It has been suggested that the Article 2(4) prohibition does not apply in

any event to limited strikes against terrorists based in another country.

Such operations, so the reasoning goes, do not ìviolate the territorial

integrity or political independenceî of the State in which they occur since

they are not directed against that Stateís personnel or property, are not

intended to affect its political independence in any way, and are limited

temporally to the period necessary to eradicate the terrorist threat. Gregory

M. Travalio, Terrorism, International Law, And The Use Of Military Force,

18 WISCONSIN INTERNATIONAL LAW JOURNAL 145, 166ñ67

(2000), citing, inter alia, Jordan J. Paust, Responding Lawfully to

International Terrorism, 8 WHITTIER LAW REVIEW 711, 716ñ7 (1986);

JOHN NORTON MOORE et. al., NATIONAL SECURITY LAW 131

(1990); LOUIS HENKIN, HOW NATIONS BEHAVE 141ñ45 (1979);

Jean Kirkpatrick and Allan Gerson, The Reagan Doctrine, Human Rights

and International Law, in RIGHT V. MIGHT 25ñ33 (Council on Foreign

Michael N. Schmitt

80
Relations 1989). This article rejects the approach, favoring, as discussed

below, one that acknowledges an infringement on sovereignty, but balances

it against other State rights.

46 S.C. Res. 731 (Jan. 21, 1992).

47 S.C. Res. 748 (Mar. 31, 1992).

48 S.C. Res. 1189 (Aug. 13, 1998). See also S.C. Res. 1044 (1996)

regarding assassination attempts against the President of Egypt, which

styled ìthe suppression of acts of international terrorism . . . an essential

element for maintenance of international peace and security.î

49 S.C. Res. 1267 (Oct. 15, 1999).

50 S.C. Res. 1363 (July 30, 2001).

51 S.C. Res. 1368 (Sept. 12, 2001).

52 S.C. Res. 1373 (Sept. 28, 2001).

53 S.C. Res. 1377 (Nov. 12, 2001). In the resolution, it adopted the

Declaration on the Global Effort to Counter Terrorism.

54 For an article arguing that there is ìa continuing process of attempting to

widen customary rights while eroding the effective powers of international

organizations,î of which Operation Enduring Freedom is an excellent

example, see Eric P.J. Myjer and Nigel D. White, The Twin Towers Attack:

An Unlimited Right to SelfñDefence?, 7 JOURNAL OF CONFLICT AND

SECURITY LAW 5 (2002).

55 See, e.g., Statute of the International Tribunal for the Former Yugoslavia

(visited June 18, 2002) <http://www.un.org/icty/index.html> [established

by S.C. Res. 827 (May 25,1993)]; Statute of the International Tribunal for

Rwanda (visited June 18, 2002) <http://www.ictr.org/ > [established by

S.C. Res. 955 (Nov. 8, 1994)]; Statute of the Special Court for Sierra Leone

(visited June 18, 2002) <http://www.sierrañleone.org/specialcourtstatute.html>

[established by S.C. Res. 1315 (Aug. 14, 2000)]. Note that the authority of

the Council to establish such tribunals was unsuccessfully challenged in an

interlocutory appeal before the Appeals Chamber of the International

Criminal Court for Yugoslavia. Prosecutor v. Tadic, Case ITñ94ñ1ñT,

Decision on Jurisdiction (Aug. 10, 1995). See George H. Aldrich,

Comment: Jurisdiction Of The International Criminal Tribunal For The

Former Yugoslavia, 90 AMERICAN JOURNAL OF INTERNATIONAL

LAW 64 (1996).

56 S.C. Res. 748 (Mar. 31, 1992) (Libya); S.C. Res. 1054 (Apr. 29, 1996)

(Sudan).

Counter-Terrorism and the Use of Force in International Law

81
57 See, e.g., Carsten Stahn, Addendum: Security Council Resolutions 1377

(2001) and 1378 (2001), ASIL Insights, Dec. 2001 (visited June 18, 2002)

<http://www.asil.org/insights/insigh77.htm>.

58 Report of the International Law Commission, 32d Sess., II(2)

YEARBOOK OF THE INTERNATIONAL LAW COMMISSION 1, 54

(1980). 

59 One important issue is whether or not Article 51 represents the entire

body of the law of selfñdefense. In the Nicaragua case, the International

Court of Justice held that the customary international law right of

selfñdefense ìcontinues to exist alongside treaty law,î specifically Article

51 of the Charter. To begin with, the article itself refers to the ìinherent

rightî of individual and collective selfñdefense. More to the point in this

inquiry is the fact that Article 51 leaves unanswered certain aspects of its

exercise. As the Court pointed out, for instance, although Article 51 sets a

threshold of ìarmed attackî for vesting of the right, there is no definition

of that term. The Charter also fails to articulate the well accepted

requirements that acts of selfñdefense be proportional and necessary.

Military and Paramilitary Activities in and against Nicaragua (Nicaragua v.

US), Merits, I.C.J. Reports 1986, para. 176 [hereinafter Nicaragua]. See

also Legality of the Threat or Use of Nuclear Weapons (Advisory Opinion),

I.C.J. Reports 1996, para. 41 [hereinafter Nuclear Weapons]. Customary

international law can prove useful in filling voids in the understanding of

selfñdefense. This fact renders the current campaign normatively

significant in that pervasive State practice over time, when the product of a

sense of legal obligation, matures into received customary international

law. The Afghanistan operations therefore represent important data points

in the development of the right of selfñdefense.

60 See Michael N. Schmitt, Computer Network Attack and the Use of Force

in International Law: Thoughts on a Normative Framework, 37

COLUMBIA JOURNAL OF TRANSNATIONAL LAW 885, 896 (1999).

61 Nicaragua, see note 59 above, para. 195 (emphasis added).

62 Note that Article 2(4) prohibition on the use of force applies only to

States.

63 In ascertaining whether an armed attack has occurred, resort is

sometimes made to the term ìaggression,î which was defined in General

Assemblyís Definition of Aggression Resolution. However, aggression is

Michael N. Schmitt

82
not wholly synonymous with armed attack. As Randelzhoffer has noted, 

The travaux preparatoires of the Definition illustrate that

a definition of ëarmed attackí was not intended. In the

special committee that worked out the Definition, the

United States, supported by other Western states,

strongly opposed tendencies to include the ëarmed

attackí. [CF the statements made by the US

representative (UN Doc. A/AC.134/S.C. 113, S.C 105, p.

17 and SC 108, p. 43), the representative of Japan (UN

Doc. A/AC.134/S.C.112), and the UK (UN Doc. A/AC.

134/SC. 113).] Like the Soviet Union [see stmt by the

Soviet Representative (UN Doc. A/AC.134/SC 105, p.

16)], they also expressed the view that the notions of ëact

of aggressioní and ëarmed attackí are not identical [see

the statement by the US representative (UN Doc.

A/AC.134/S.C. 105, p. 17)]. 

Albrecht Randelzhofer, Article 51, in THE CHARTER OF THE UNITED

NATIONS: A COMMENTARY 661, 668 (Bruno Simma ed., 1995).

64 Letter from Daniel Webster to Lord Ashburton (Aug. 6, 1842), 29

BRITISH AND FOREIGN STATE PAPERS 1129, 1138 (1840ñ1).

65 Nicaragua, see note 59 above, para. 176.

66 Nuclear Weapons, see note 59 above, para. 41. See also

RESTATEMENT (THIRD) OF THE FOREIGN RELATIONS LAW OF

THE UNITED STATES 905 (1987). Ian Brownlie labels proportionality

ìthe essence of selfñdefence.î IAN BROWNLIE, INTERNATIONAL

LAW AND THE USE OF FORCE BY STATES 279 n. 2 (1963).

67 Nuclear Weapons, see note 59 above, para. 41. 

68 Id., para. 42. There are, as noted in the discussion of selfñdefense,

competing views of proportionality. India argued that the principle meant a

nuclear weapon could not be used except in response to a nuclear attack.

But even in such a case, so India argued, the use of nuclear weapons would

be malum in se. Thus, any nuclear reprisal would be unlawful. Written

Statement of the Government of India, June 20, 1995 (Legality of the

Threat or Use of Nuclear Weapons), at 2ñ3. Other approaches include

ìproportional to the harm caused,î vice ìtechnique employed to cause the

Counter-Terrorism and the Use of Force in International Law

83
harm,î and ìproportional to the force needed to cause the other side to

desist.î Compare the approach of the Netherlands and United States, both

of which argued that the legality would be situational, with that of India.

Observations of the Government of the Kingdom of the Netherlands, June

16, 1995 (Legality of the Threat or Use of Nuclear Weapons), at 12; Written

Statement of the Government of the United States of America, June 20,

1995 (Legality of the Threat or Use of Nuclear Weapons), at 30.

69 In a slightly different context, this approach lies at the heart of

compellance strategies. On the issue of affecting an enemyís

decisionñmaking, see Jeanne M. Meyer, Tearing Down the FaÁade: A

Critical Look at the Current Law on Targeting the Will of the Enemy and

Air Force Doctrine, 51 AIR FORCE LAW REVIEW 143 (2001).

70 Estimates of civilian casualties vary widely. Compare, e.g., Marc W.

Herold, A Dossier on Civilian Victims of United Statesí Aerial Bombing of

Afghanistan: A Comprehensive Accounting, Dec. 10, 2001 (visited June 18,

2002) <http://www.cursor.org/stories/civilian_deaths.htm> (approximately

4,000 by Jan 1, 2002) with Carl Connetta, Operation Enduring Freedom:

Why a Higher Rate of Civilian Bombing Casualties, Jan. 18, 2002 (visited

June 18, 2002) <http://www.comw.org/pda/0201oef.html#ref7>

(1,000ñ13,000 over the same period). A Human Rights Watch Report is

forthcoming on the subject (unreleased as of June 19, 2002).

71 Protocol Additional (I) to the Geneva Convention of 12 August 1949, and

Relating to the Protection of Victims of International Armed Conflicts, arts.

51.5(a) & 57.2(a)(iii) & (b), Dec. 12, 1977, 1125 U.N.T.S. 3, 16

INTERNATIONAL LEGAL MATERIALS 1391 (1977), reprinted ADAM

ROBERTS & RICHARD GUELFF, DOCUMENTS ON THE LAWS OF

WAR 419 (3d ed. 2000). On proportionality, see William J. Fenrick, The

Rule of Proportionality and Protocol Additional I in Conventional Warfare,

98 MILITARY LAW REVIEW 91 (1982); Judith G. Gardam,

Proportionality and Force in International Law, 87 AMERICAN

JOURNAL OF INTERNATIONAL LAW 391 (1993).

72 Yoram Dinstein has rejected the terminology ìanticipatoryî in favor of

ìinterceptiveî on the basis that former term suggests that preventive actions

in the face of a ìforeseeableî armed attack are legitimate. For Professor

Dinstein, the question is whether or not the ìother side has committed itself

to an armed attack in an ostensibly irrevocable way.î As he explains, ì[t]he

Michael N. Schmitt

84
crucial question is who embarks upon an irreversible course of action,

thereby crossing the Rubicon. This, rather than the actual opening of fire,

is what casts the die and forms what may be categorized as an incipient

armed attack. It would be absurd to require that the defending State should

sustain and absorb a devastating (perhaps a fatal) blow, only to prove an

immaculate conception of selfñdefence.î YORAM DINSTEIN, WAR,

AGGRESSION AND SELFñDEFENSE 172 (3rd ed. 2001).

73 See, e.g., Oscar Schachter, The Right of States to Use Armed Force, 82

MICHIGAN LAW REVIEW 1620, 1634ñ35 (1984). 

74 Schmitt, see note 60 above, at 932.

75 See, e.g., Antonio Cassese, Terrorism is also Disrupting Some

Crucial Legal Categories of International Law, European

Journal of International Law Discussion Forum (visited June 18,

2002) <http://www.ejil.org/forum_WTC/nyñcassese.html>. See also

Giorgio Gaja, In What Sense Was There an ìArmed Attackî?, European

Journal of International Law Discussion Forum (visited June 18, 2002)

<http://www.ejil.org/forum_WTC/nyñgaja.html>.

76 Irelandís Ambassador to the United Nations, who was acting as President

of the Security Council, noted the unanimous support of the Council

following the briefing on the United Statesí and United Kingdomís

operations in selfñdefense. Christopher S. Wren, U.S. Advises UN Council

More Strikes Could Come, N.Y. TIMES, Oct. 9, 2001, at B5.

77 S.C. Res.1378 (Nov. 14, 2002); S.C. Res. 1386 (Dec. 20, 2001); S.C.

Res. 1390 (Jan. 16, 2002). Specific reference was made to Usama bin

Laden and the Al Qaeda network in January resolution.

78 For a preñ9/11 discussion of the alternatives, and the appropriateness of

each, see Walter Gary Sharp, The Use of Armed Force Against Terrorism:

American Hegemony or Impotence?, 1 CHICAGO JOURNAL OF

INTERNATIONAL LAW 37 (2000).

79 A crime against humanity involves the commission of certain acts,

including murder and ìother inhumane acts . . . causing great suffering, or

serious injury to body or to mental or physical healthî when committed as

part of a widespread or systematic attack directed against any civilian

population. (Rome Statute for the International Criminal Court, art. 7.1),

reprinted in 37 INTERNATIONAL LEGAL MATERIALS 999 (1998),

M. CHERIF BASSIOUNI, THE STATUTE OF THE INTERNATIONAL

Counter-Terrorism and the Use of Force in International Law

85
COURT: A DOCUMENTARY HISTORY 39 (1999), and (visited June 18,

2002) <www.un.org/law/icc/texts/romefra.htm>. Widespread consensus

exists that the attacks of 9/11 constituted crimes against humanity. For an

analysis of its applicability to the 9/11 attacks, see Cassese, see note 75

above.

80 Hague Convention for the Suppression of Unlawful Seizure of Aircraft,

Dec. 16, 1970, art. 1, 22 U.S.T. 1641, 10 International Legal Materials 133

(1971); Tokyo Convention on Offences and Certain Other Acts Committed

on Board Aircraft, Sept. 14, 1963, 20 U.S.T. 2941, 704 U.N.T.S. 219;

Montreal Convention on the Suppression of Unlawful Acts Against The

Safety of Civil Aviation, Sept. 23, 1971, 24 U.S.T. ß 565, T.I.A.S. No.

7570; Convention for the Suppression of Unlawful Seizure of Aircraft,

Dec. 16, 1970, art. 1, 22 U.S.T. 1641, 860 U.N.T.S. 105, 107. On the

applicability, or difficulties thereof, of the treaties to the 9/11 attacks, see

Arnold N. Pronto, Comment, ASIL Insights, Sept. 2001 (visited June 18,

2002) <http://www.asil.org/insights/insigh77.htm>.

81 Professor M. Cherif Bassiouni has convincingly argued that the

international law governing this topic is not comprehensive.

ì[G]overnments have avoided developing an international legal regime to

prevent, control, and suppress terrorism, preferring instead the hodgepodge

of thirteen treaties that currently address its particular manifestations.î

M. Cherif Bassiouni, Legal Control of International Terrorism: A

PolicyñOriented Assessment, 43 HARVARD INTERNATIONAL LAW

JOURNAL 83 (2002).

82 Antiterrorism Act of 1990, 18 United States Code ßß 2331 et seq.

83 18 United States Code ß 32.See Jordan J. Paust, Addendum: Prosecution

of Mr. bin Laden et al. for Violations of International Law and Civil

Lawsuits by Various Victims, ASIL Insights, Sept. 21, 2001 (visited June

18, 2002) <http://www.asil.org/insights/insigh77.htm>. Professor Paust

also discusses the possibility of civil suits against the perpetrators.

84 David Johnson, Don Van Nata & Judith Miller, Qaeda Lieutenants Form

Terror Alliance, INTERNATIONAL HERALD TRIBUNE, June 17, 2002,

at 1.

85 On the continuing operations of the organization, see David Johnston,

Don Van Natta Jr. and Judith Miller, Qaeda's New Links Increase Threats

From FarñFlung Sites, N.Y. TIMES, June 16, 2002, at 1.

Michael N. Schmitt

86
86 UN CHARTER, 2(4).

87 Randelzhoffer, Article 2(4), see note 41 above, at 117. See also

Declaration on Principles of International Law Concerning Friendly

Relations and Cooperation Among States in Accordance with the Charter

of the United Nations: 

Every State has a duty to refrain in its international

relations from the threat or use of force against the

territorial integrity or political independence of any

State, or in any other manner inconsistent with the

purposes of the United Nations. Such a threat or use of

force constitutes a violation of international law and the

Charter of the United Nations and shall never be

employed as a means of settling international issues. 

G.A. Res. 2625 (XXV), UN GAOR, 25th Sess., annex, UN Doc.

A/Res/2625 (1970), reprinted in 65 AMERICAN JOURNAL OF

INTERNATIONAL LAW 243 (1971) and in KEY RESOLUTIONS OF

THE UNITED NATIONS GENERAL ASSEMBLY, 1946ñ1996 (Dietrich

Rauschning, Katja Wiesbrock & Martin Lailach eds., 1997), at 3

[hereinafter Declaration on Friendly Relations]. The resolution was

adopted by acclamation.

88 ìAggression is the use of armed force by a State against the . . . territorial

integrity . . . of another State.î Definition of Aggression, annex, art. 1, G.A.

Res. 3314 (XXIX), UN GAOR, 29th Sess., Supp. No. 31, at 142, UN Doc.

A/9631 (1975), 13 INTERNATIONAL LEGAL MATERIALS 710 (1974).

Additionally, pursuant to Article 3, aggression includes ì[t]he invasion or

attack by the armed forces of a State of the territory of another State. . . .î

89 S.S. Lotus (Fr. v. Turk.) 1927 P.C.I.J. (ser. A) No. 10, at 4, 88 (Moore, J.,

dissenting). 

90 Declaration on Friendly Relations, see note 87 above.

91 Declaration on Measures to Eliminate International Terrorism, G.A. Res.

49/60, UN GAOR 6th Comm., 49th Sess., 84th plen. mtg., UN Doc.

A/49/743 (1994); Declaration to Supplement the 1994 Declaration on

Measures to Eliminate International Terrorism, G.A. Res. 51/210, UN

GAOR 6th Comm., 51st Sess., 88th plen. mtg., UN Doc. A/51/631 (1996).

92 Professor Robert Turner perceptively offered an analysis along these

lines in the aftermath of the September 11 attacks. Robert F. Turner,

Counter-Terrorism and the Use of Force in International Law

87
International Law And The Use Of Force In Response To The World Trade

Center And Pentagon Attacks, Jurist, (visited June 18, 2002)

<http://jurist.law.pitt.edu/forum/forumnew34.htm>. On the subject of

selfñhelp, see also Guy B. Roberts, SelfñHelp in Combating

StateñSponsored Terrorism: Self Defense and Peacetime Reprisals, 19

CASE WESTERN RESERVE JOURNAL OF INTERNATIONAL LAW

243 (1987); Franz W. Paasche, The Use of Force in Combating Terrorism,

25 COLUMBIA JOURNAL OF TRANSNATIONAL LAW 377 (1987);

Oscar Schachter, The ExtrañTerritorial Use of Force against Terrorist

Bases, 11 HOUSTON JOURNAL OF INTERNATIONAL LAW 309

(1989).

93 On the Cambodian incursions, see Timothy Guiden, Defending

America's Cambodian Incursion, 11 ARIZONA JOURNAL OF

INTERNATIONAL AND COMPARATIVE LAW 215 (1994); John Fried,

United States Military Intervention in Cambodia in the Light of

International Law, reprinted in 3 THE VIETNAM WAR AND

INTERNATIONAL LAW 100 (Richard Falk, ed. 1972); International Law

and Military Operations Against Insurgents in Neutral Territories, 68

COLUMBIA LAW REVIEW 1127 (1968). 

94 See statement of [then] Israeli Ambassador to the UN, Benjamin

Netanyahu, UN Doc. S/PV.2615, at 86ñ7 (Oct. 4, 1985). 

95 S.C. Res. 573 (Oct. 4, 1985).

96 Id.

97 See W. Michael Reisman, International Legal Responses to Terrorism,

22 HOUSTON JOURNAL OF INTERNATIONAL LAW 3, 53 (1999);

G.A. Res. 45/150, UN GAOR 3d Comm., 45th Sess., 69th plen. mtg., UN

Doc. A/Res/45/150 (1990).

98 First Operation Provide Comfort, later Northern Watch. The author was

Staff Judge Advocate of the operations during this period.

99 See, e.g., Department of State, 1999 Country Reports on Human

Rights Practices: Turkey (visited June 18, 2002)

<//www.state.gov/www/global/human_rights/1999_hrp_report/turkey.html>

100 Ruth Wedgwood, Responding to Terrorism: The Strikes Against bin

Laden, 24 YALE JOURNAL OF INTERNATIONAL LAW 559 (1999);

Leah M. Campbell, Defending Against Terrorism: A Legal Analysis of the

Decision to Strike Sudan and Afghanistan, 74 TULANE LAW REVIEW

1067 (2000).

Michael N. Schmitt

88
101 On the confusion surrounding whether the facility was involved in

terrorist activities, see Vernon Loeb, U.S. Wasnít Sure Plant Had Nerve Gas

Role; Before Sudan Strike, CIA Urged More Tests, WASHINGTON POST,

Aug. 21, 1999, at A1.

102 Reisman, see note 97 above, at 54. 

103 In S.C. Res. 1291 (Feb. 24, 2000), the Council authorized the United

Nations Organization Mission in the Democratic

R e p u b l i c of the Congo. For details and background, see

<http://www.un.org/Depts/dpko/monuc/monuc_body.htm> (visited June

18, 2002).

104 On the Caroline incident in the context of the issue at hand, see

Reisman, see note 97 above, at 42ñ47. On the facts, see R.Y. Jennings, The

Caroline and McLeod Cases, 32 AMERICAN JOURNAL OF

INTERNATIONAL LAW 82 (1938).

105 Letter from Lord Ashburton to Daniel Webster (July 28, 1842), 30

BRITISH AND FOREIGN STATE PAPERS 195. 

106

A necessity of selfñdefence, instant, overwhelming,

leaving no choice of means, and no moment for

deliberation. It will be for it to show, also, that the local

authorities of Canada, even supposing the necessity of

the moment authorized them to enter the territories of

The United States at all, did nothing unreasonable or

excessive; since the act, justified by the necessity of

selfñdefence, must be limited by that necessity, and kept

clearly within it. It must be shown that admonition or

remonstrance to the persons on board the Caroline was

impracticable, or would have been unavailing; it must be

shown that dayñlight could not be waited for; that there

could be no attempt at discrimination between the

innocent and the guilty; that it would not have been

enough to seize and detain the vessel; but that there was

a necessity, present and inevitable, for attacking her in

the darkness of the night, while moored to the shore, and

while unarmed men were asleep on board, killing some

and wounding others, and then drawing her into the

Counter-Terrorism and the Use of Force in International Law

89
current, above the cataract, setting her on fire, and,

careless to know whether there might not be in her the

innocent with the guilty, or the living with the dead,

committing her to a fate which fills the imagination with

horror. A necessity for all this, the Government of The

United States cannot believe to have existed. 

Jennings, see note 104 above, at 89 (quoting Daniel Webster).

107 Murphy, Contemporary Practice 2002, see note 38 above, at 244. The

situation caused divisions within the Taliban and Afghan religious

leadership. Clearly, unanimity did not exist as to how to respond to the US

demands. John F. Burns, Afghans Coaxing bin Laden, But U.S. Rejects

Clerics' Bid, N.Y. TIMES, Sept. 21, 2001, at A1.

108 Murphy, Contemporary Practice 2002, see note 38 above, at 244.

109 Elisabeth Bumiller, President Rejects Offer By Taliban For

Negotiations, N.Y. TIMES, Oct. 15, 2001, at A1.

110 S.C. Res. 1333 (2000).

111 UK Press Release, see note 8 above, at paras. 14ñ15.

112 On the conduct of forces in another country, see THE HANDBOOK OF

THE LAW OF VISITING FORCES (Dieter Fleck ed., 2001).

113 Address Before a Joint Session of the Congress, see note 15 above, at 1349. 

114 US Letter, see note 21 above.

115 UK Press Release, see note 8 above, 8, para. 16.

116 See id. generally. See also the update to the UK press release. United

Kingdom Press Release, 10 Downing Street Newsroom, Responsibility for

the Terrorist Atrocities in the United States, Nov. 14, 2001 (visited June 18,

2002) <http://www.pm.gov.uk/news.asp?NewsId=3025>. 

117 UK Press Release, see note 8 above, para.12.

118 Id., para. 13.

119 On the issue of State responsibility, see Gregory Townsend, State

Responsibility for Acts of De Facto Agents, 14 ARIZONA JOURNAL OF

INTERNATIONAL AND COMPARATIVE LAW 635 (1997); Ian

Brownlie, International Law and the Activities of Bands, 7

INTERNATIONAL AND COMPARATIVE LAW QUARTERLY 712

(1958).

120 Declaration on Measures to Eliminate International Terrorism, G.A.

Res. 49/60, UN GAOR 6th Comm., 49th Sess., 84th plen. mtg., UN Doc.

Michael N. Schmitt

90
A/49/743 (1994); Declaration to Supplement the 1994 Declaration on

Measures to Eliminate International Terrorism, G.A. Res. 51/210, UN

GAOR 6th Comm., 51st Sess., 88th plen. mtg., UN Doc. A/51/631 (1996).

121 ìEvery state has the duty to refrain from organizing, instigating,

assisting or participating in acts of civil strife or terrorist acts in another

State or acquiescing in organized activities within its territory directed

towards the commission of such acts, when the acts referred to in the

present paragraph involve a threat or use of force.î Declaration on Friendly

Relations, see note 87 above, prin. 1.

122 ìNo state shall organize, assist, foment, finance, incite, or tolerate

subversive, terrorist or armed activities directed toward the violent

overthrow of another regime . . .î G.A. Resolution 2131, UN GOAR, 20th

Sess., Supp. No. 14, at 107, UN Doc. A/6221 (1965).

123

The organization, or the encouragement of the

organization, by the authorities of a State, of armed

bands within its territory or any other territory for

incursions into the territory of another State, or the

toleration of the organization of such bands in its own

territory, or the toleration of the use by such armed bands

of its territory as a base of operations or as a point of

departure for incursions into the territory of another

State, as well as direct participation in or support of such

incursions. 

Draft Code of Offenses Against the Peace and Security of Mankind, art.

2(4), (visited June 18, 2002) <http://www.un.org/law/ilc/texts/offfra.htm>.

124 Corfu Channel Case (Merits), 1949 I.C.J. Rep. 4, 22.

125 See discussion in JAMES CRAWFORD, THE INTERNATIONAL

LAW COMMISSIONíS ARTICLES ON STATE RESPONSIBILITY:

INTRODUCTION, TEXT AND COMMENTARIES 77ñ85 (2002).

Article 2 of the International Law Commissionís Articles on State

Responsibility (adopted by the Commission in 2001) provides that ìThere

is an internationally wrongful act of a State when conduct consisting of an

act or omission: (a) is attributable to the State under international law; and

(b) constitutes a breach of an international obligation of the State.î

International Law Commission, Articles on State Responsibility, reprinted

Counter-Terrorism and the Use of Force in International Law

91
in id. at 61. These elements have been articulated in a number of tribunals.

Among those referenced specifically by Professor Crawford are:

Phosphates in Morocco, Preliminary Objections, 1938, P.C.I.J., Series A/B,

No. 74, p. 10; United States Diplomatic and Consular Staff in Tehran, I.C.J.

Reports 1980, p. 3; Military and Paramilitary Activities in and against

Nicaragua (Nicaragua v. US), Merits, I.C.J. Reports 1986, p. 14, 117ñ118,

para. 226; GabcikovoñNagymaros Project (Hungary/Slovakia), I.C.J.

Reports 1997, p. 7, 54, para. 78. 

126 The Commentary to the ILC Articles on State Responsibility describes

a ìstateî as ìa real organized entity, a legal person to act under international

law.î Crawford, see note 125 above, at 82 (para. 5 of commentary to art. 2).

127 Articles on State Responsibility, see note 125 above, arts. 34ñ37.

Restitution is reestablishing ìthe situation which existed before the wrongful

act was committedî (art. 35); compensation is covering any financially

assessable damage not made good by restitution (art. 36); satisfaction is ìan

acknowledgement of the breach, an expression of regret, a formal apology or

another appropriate modalityî that responds to shortfalls in restitution and

compensation when making good the injury caused (art. 37).

128 Id., art. 49.1.

129 Crawford, see note 125 above, at 281.

130 Articles on State Responsibility, see note 125 above, art. 52.3(a).

131 Id., art. 51.

132 Id., art. 52.1.

133 Certain countermeasures employing force are permissible. An example

would be sending agents into a State to apprehend a terrorist whom that

State wrongfully refused to extradite. Mary Ellen OíConnell,

Lawful Responses to Terrorism, Jurist (visited June 18, 2002) <

http://jurist.law.pitt.edu/forum/forumnew30.htm>.

134 Articles on State Responsibility, see note 125 above, art. 50.1(a).

135 Id., art. 8.

136 Nicaragua, see note 59 above, para. 115. 

137 Id., para. 86.

138 Articles of State Responsibility, see note 125 above, art. 11.

139 United States Diplomatic and Consular Staff in Tehran (Iran v. USA),

1980 I.C.J. 3.

140 According to the court, Iranian authorities were ìfully aware of their

obligations to protect the premises of the U.S. Embassy and its diplomatic

Michael N. Schmitt

92
and consular staff from any attack [,] . . . had the means at their disposal to

perform their obligations [but,] . . . completely failed to comply.î Id., para. 68.

141 Id., para. 73.

142 Id., para. 74.

143 This reality explains why the prohibition on forcible countermeasures is

reasonable; the ban is compensated for in those cases where one might

most want to engage in them ó when victimized by an armed attack ó by

the existence of the right to selfñdefense. Conversely, the various limits on

selfñdefense are compensated for by the fact that once the need for

selfñdefense vanishes, the State that committed the wrongful attack

remains liable for the consequences under the law of State responsibility.

The classic example is the Iraqi invasion of Kuwait in 1990. In S.C. Res.

681 (Apr. 3, 1991), the Security Council found that ìIraq . . . is liable under

international law for any direct loss, damage, including environmental

damage and the depletion of natural resources, or injury to foreign

Governments, nationals and corporations, as a result of Iraqís unlawful

invasion and occupation of Kuwait.î It subsequently established the United

Nations Compensation Commission to handle claims in S.C. Res. 692

(May 20, 1991). 

144 For instance, Oscar Schachter has argued ìWhen a government provides

weapons, technical advice, transportation, aid and encouragement to

terrorists on a substantial scale, it is not unreasonable to conclude that an

armed attack is imputable to the government.î Oscar Schachter, The Lawful

Use of Force by a State Against Terrorists in Another Country, reprinted in

HENRY H. HAN, TERRORISM AND POLITICAL VIOLENCE 250

(1993). See also Alberto Coll, The Legal and Moral Adequacy of Military

Responses to Terrorism, 81 PROCEEDINGS OF THE AMERICAN

SOCIETY OF INTERNATIONAL LAW 297 (1987). 

145 Nicaragua, see note 59 above (Schwebel dissent) at 258ñ259, para. 6.

146 International Criminal Tribunal for Yugoslavia, Case ITñ94ñ1,

Prosecutor v. Tadic, 38 INTERNATIONAL LEGAL MATERIALS 1518

(1999), at paras. 120 & 145.

147 Glennon, see note 3 above, at 540ñ41.

148 For instance, Michael Reisman has identified nine basic categories of

unilateral uses of force that enjoyed a significant degree of community

support: ìselfñdefense, which has been construed quite broadly;

Counter-Terrorism and the Use of Force in International Law

93
selfñdetermination and decolonization; humanitarian intervention;

intervention by the military instrument within spheres of influence and

critical defense zones; treatyñsanctioned interventions within the territory

of another State; use of the military instrument for the gathering of

evidence in international proceedings; use of the military instrument to

enforce international judgments; and counter measures, such as reprisals

and retorsions.î W. Michael Reisman, Criteria for the Lawful Use of Force

in International Law, 10 YALE JOURNAL OF INTERNATIONAL LAW

279, 281 (1985). See also W. Michael Reisman, Article 2(4): The Use of

Force in Contemporary International Law, 78ñ79 PROCEEDINGS OF

THE AMERICAN SOCIETY OF INTERNATIONAL LAW 74, 79ñ84

(1984ñ85); W. Michael Reisman, War Powers: The Operational Code of

Competence, 83 AMERICAN JOURNAL OF INTERNATIONAL LAW

777 (1989). 

149 Such as physical survival and security for individuals and the tangible

or intangible objects on which they rely, human dignity, social progress and

quality of life, and ìthe right of peoples to shape their own political

community.î These aims derive from those expressed in the Preamble to

the UN Charter:

To save succeeding generations from the scourge of war,

which twice in our lifeñtime has brought untold sorrow

to mankind, and to reaffirm faith in fundamental human

rights, in the dignity and worth of the human person, in

the equal rights of men and women and of nations large

and small, and to establish conditions under which

justice and respect for the obligations arising from

treaties and other sources of international law can be

maintained, and to promote social progress and better

standards of life in larger freedom. 

UN Charter, pmbl. The final aim was articulated in W. Michael Reisman,

Allocating Competences to Use Coercion in the PostñCold War World:

Practices, Conditions, and Prospects, in LAW AND FORCE IN THE

NEW INTERNATIONAL ORDER 26, 45 (Lori Damrosch & David J.

Scheffer eds., 1991).

150 Marian Nash Leich, U.S. Practice 80 AMERICAN JOURNAL

INTERNATIONAL LAW 612, 633 (1986); Gregory Intoccia, American

Bombing of Libya: An International Legal Analysis, 19 CASE WESTERN

Michael N. Schmitt

94
RESERVE JOURNAL OF INTERNATIONAL LAW 177 (1987); Jeffrey

A. McCredie, The April 14, 1986 Bombing of Libya: Act of SelfñDefense or

Reprisal?, 19 CASE WESTERN RESERVE JOURNAL OF

INTERNATIONAL LAW 215 (1987); David Turndorf, The U.S. Raid on

Libya: A Forceful Response to Terrorism, 14 BROOKLYN JOURNAL OF

INTERNATIONAL LAW 187 (1988).

151 See Reisman, International Legal Responses, see note 97 above, 33ñ34,

for a detailed description of the international reaction. See also Stuart G.

Baker, Comparing the 1993 U.S Airstrike on Iraq to the 1986 Bombing of

Libya: The New Interpretation of Article 51, 24 GEORGIA JOURNAL OF

INTERNATIONAL AND COMPARATIVE LAW 99 (1994).

152 Israelis Praise It While Arabs Vow to Avenge It, CHICAGO TRIBUNE,

Apr. 16, 1986, at A9. 

153 The NATOñRussia Council, approved in May 2002, is

specifically tasked with countering terrorism. See Declaration

by Heads of State and Government of NATO Member States

and the Russian Federation, May 28, 2002 (visited June 18,

2002) <http://www.nato.int/docu/basictxt/b020528e.htm>.

154 William Clinton, Address to the Nation on the Strike on Iraqi

Intelligence Headquarters, 29 WEEKLY COMPILATION OF

PRESIDENTIAL DOCUMENTS 1180ñ81 (June 26, 1993). For an

excellent analysis on the state of international law regarding

counterñterrorism in the wake of the US strikes, see Robert J. Beck and

Anthony Clark Arend, ìDonít Tread On Usî: International Law and

Forcible State Responses To Terrorism, 12 WISCONSIN

INTERNATIONAL LAW JOURNAL 153 (1994). See also Robert F.

Teplitz, Taking Assassination Seriously: Did the United States Violate

International Law in Responding to the Iraqi Plot to Kill George Bush, 28

CORNELL INTERNATIONAL LAW JOURNAL 569 (1995).

155 Baker, see note 151 above, at 99ñ101.

156 On the extent to which the Council was satisfied with the US evidence,

see U.S. Photo Evidence Convinces the UN, TORONTO STAR, June 28,

1993, at A13. 

157 Text of the State Department Report in Libya Under Qaddafi, N.Y.

TIMES, Jan. 9, 1986, at A6.

158 The accused bombers were tried in Her Majestyís Advocate v.

Abdelbaset ali Mohamed al Megrahi and Al Amin Khalifa Fhimah, Scot.

Counter-Terrorism and the Use of Force in International Law

95
High Court of Justiciary at Camp Zeist, Case No. 1475/99. Megrahi was

found guilty and sentenced to life imprisonment in January 2001; the Court

accepted the allegation that he was a member of Libyaís Jamahariya

Security Organization. In March 2002, Megrahiís appeal was denied.

Abdelbaset Ali Mohmed Al Megrahi v. Her Majestyís Advocate, Appeal

Court, High Court of Justiciary, Appeal No: C104/01. Negotiations over

Libyan compensation for the victimsí families have been ongoing for some

time. See, e.g., Rob Crilly, Libya Denies Offer of (Pounds) 1.8bn Deal for

Lockerbie Families, THE HERALD (Glasgow), May 30, 2002, at 2.

159 William Clinton, Remarks on Departure for Washington, D.C., from

Marthaís Vineyard, Massachusetts, 34 WEEKLY COMPILATION OF

PRESIDENTIAL DOCUMENTS 1642 (Aug. 20, 1998).

160 Letter from the Permanent Representative of the United

States of America to the President of the Security Council (Aug.

20, 1998), UN Doc. S/1998/780 (1998) (visited June 18, 2002)

<http://www.undp.org/missions/usa/s1998780.pdf>.

161 Pakistan protested the violation of its airspace. Letter from the

Permanent Representative of Pakistan to the President of the Security

Council, Aug. 24, 1998, UN Doc. S/1998/794 (1998). 

162 The international reaction is well described in Sean D. Murphy,

Contemporary Practice of the United States Relating to International Law,

93 AMERICAN JOURNAL OF INTERNATIONAL LAW 161, 164ñ5

(1999).

163 Letter from the Charge díAffaires of the Permanent Mission of Kuwait

to the United Nations Addressed to the President of the Security Council,

Aug. 21, 1998, UN Doc. S/1998/789 (1998).

164 Letter from the Permanent Representative of the Sudan to the United

Nations Addressed to the President of the Security Council, Aug. 21, 1998,

UN Doc. S/1998/786, annex (1998); Letter from the Permanent

Representative of Namibia to the United Nations Addressed to the

President of the Security Council, Aug. 25, 1998, UN Doc. S/1998/802

(1998) (Group of African States request); Letter from the Charge díAffaires

A.I. of the Permanent Mission of Qatar to the United Nations Addressed to

the President of the Security Council, Aug. 21, 1998, UN Doc. S/1998/790

(1998) (Group of Islamic States request); Letter from the Charge díAffaires

of the Permanent Mission of Kuwait to the United Nations Addressed to the

Michael N. Schmitt

96
President of the Security Council, Aug. 21, 1998, UN Doc. S/1998/791

(1998) (League of Arab States request).

165 Tim Weiner & Steven Lee Myers, After the Attacks: The Overview,

Flaws in the U.S. Account Raise Questions on Strike in Sudan, N.Y.

TIMES, Aug. 19, 1998, at A2. 

166 W. Michael Reisman, The Raid on Baghdad: Some Reflections on its

Lawfulness and Implications, 5 EUROPEAN JOURNAL OF

INTERNATIONAL LAW 120, 121 (1994). He further notes ìa prerequisite

for appraisal of the lawfulness of an incident . . . is an identification of the

yardstick of lawfulness actually being used by the relevant actors.î Id.

167 See, e.g., Department of State, Human Rights Country Report:

Afghanistan, Mar. 4, 2002 (visited June 18, 2002)

<http://www.state.gov/g/drl/rls/hrrpt/2001/sa/8222.htm>. See also the

various reports by Human Rights Watch available at

http://hrw.org/reports/world/afghanistanñpubs.php> (visited June 18,

2002). 

168 Mary Ellen OíConnell, Evidence of Terror, 7 JOURNAL OF

CONFLICT AND SECURITY LAW 19, 22ñ28 (2002).

169 Professor OíConnell notes that the Court referred to the need for

ìsufficient proofî [at 437, para. 101], which she argues equates by

implication to convincing proof. Id. at 24.

170 Id. at 25, citing Christopher Greenwood, International Law and the

United Statesí Air Operation Against Libya, 89 WEST VIRGINIA LAW

REVIEW 933, 935 (1987) [ìsufficiently convincingî]; Jules Lobel, The

Use of Force to respond to Terrorist Attacks: The Bombing of Sudan and

Afghanistan, 24 YALE JOURNAL OF INTERNATIONAL LAW 537, 538

(1999) [clear and stringent evidentiary standard]; LOUIS HENKIN, HOW

NATIONS BEHAVE (2d ed. 1979) [the attack must be ìclear,

unambiguous, subject to proof, and not easily open to misinterpretation or

fabricationî].

171 US Letter, see note 21 above.

172 Robertson Statement, see note 33 above.

173 Jonathan I. Charney, Editorial Comments: The Use of Force Against

Terrorism and International Law, 95 AMERICAN JOURNAL OF

INTERNATIONAL LAW 835, 836 (2001).

174 See Bill Gertz, U.S. Intercepts from Libya Play Role in Berlin Bomb

Trial, WASHINGTON TIMES, Nov. 19, 1997, at A13. The United States

Counter-Terrorism and the Use of Force in International Law

97
provided intercepted communications gathered by the National Security

Agency.

175 According to the Egyptian Minister of Interior, ìas many as 80,000

people may have been trained in Afghanistan under bin Laden.î 1 THE

TERRORIST THREAT (no. 2), Apr. 2002, at 2.

Michael N. Schmitt

98
The George C. Marshall 

European Center for Security Studies

Dr. John P. Rose

Director

MG (Ret.) Michael J. McCarthy, USAF

Deputy Director

MG (Ret.) Winfried Dunkel, GE

Deputy Director

College of International and Security Studies

Dr. Gary L. Guertner

Dean

CAPT Lawson R. Almand

Dr. John L. Clarke

Editorial Review

Ms. Sara C. Holman

Editor, Marshall Center Papers

Mr. William L. Winkle

Distribution

Marshall Center Papers Editorial Board Reviewers

Dr. Andrew L. Ross

Dr. Stephen L. White
The Marshall Center Papers

No. 1 - Europeís New Defense Ambitions:

Implications for NATO, the US, and Russia 

by Peter van Ham

April 2000

No. 2 - The Transformation of Russian 

Military Doctrine: Lessons Learned 

from Kosovo and Chechnya 

by Alexei G. Arbatov

July 2000

No. 3 - Cooperative Security: 

New Horizons for International Order

by Richard Cohen and 

Michael Mihalka

April 2001

No. 4 - Western Unity and the Transatlantic 

Security Challenge 

by Peter van Ham and

Richard L. Kugler

June 2002
The Marshall Center Papers

Editorial Advisory Board

Prof. Evgeniy Bazhanov

Vice-President, Russian Diplomatic Academy

Prof. Dr. Wilfried von Bredow

Institut f ̧r Politikwissenschaft,Universit‰t Marburg

Dr. Paul Cornish

Centre for Defence Studies, Kingís College London

Dr. Christopher Dandeker

Head, Department of War Studies, Kingís College London

Dr. Robert H. Dorff

Chairman, Dept. of National Security and Strategy, US Army War College

Prof. Dr. Heinz Gaertner

Institut f ̧r Politikwissenschaft, Universit‰t Wien

Prof. Dr. Ferenc Gazdag

Director, Institute for Strategic and Defence Studies, Budapest

Dr. Thomas B. Grassey

Director, US Naval War College Press

Prof. Dr. Ali M. Karaosmanoglu

Chairman, Dept. of International Relations, Bilkent University

Dr. Jacob Kipp

Senior Analyst, Foreign Military Studies Office 

US Army Combined Arms Center

Dr. Charles A. Kupchan

Senior Fellow, Council on Foreign Relations, Washington

Dr. Friedemann M ̧ller

Stiftung Wissenschaft und Politik, Berlin

Dr. Frances Pilch

Political Science Department., US Air Force Academy

Dr. Andrew L. Ross 

Strategic Research Department, US Naval War College

Dr. Dmitri Trenin

Deputy Director, Carnegie Endowment for International Peace, Moscow Center

Dr. Thanos Veremis

Constantine Karamanlis Professor in Hellenic and Southeastern

European Studies, The Fletcher School of Law and Diplomacy 

Tufts University

Prof. Dr. Peter M. E. Volten

Director, Centre for European Security Studies, University of Groningen 

Dr. Stephen L. White

Department of Politics, University of Glasgow

CCooperative Security: Two Views
Counter-Terrorism and the 

Use of Force in International Law

By Michael N. Schmitt, Professor of International Law and

Director, Executive Program in International and Security Affairs,

George C. Marshall European Center for Security Studies,

Garmisch-Partenkirchen, Germany.

On September 11, 2001, Al Qaeda terrorists flew two 

commercial airplanes into the World Trade Center and one into

the Pentagon. A fourth crashed into the Pennsylvania

countryside. Nearly 3,000 innocents died in the attacks. This

Marshall Center Paper explores the legality of the US response t

9/11 against Al Qaeda and the Taliban. Although States have

conducted military counter-terrorist operations in the past, the

scale and scope of Operation Enduring Freedom may well signa

a sea change in strategies to defend against terrorism. This

paper explores the normative limit on counter-terrorist operations

Under what circumstances can a victim State react forcibly to an

act of terrorism? Against whom? When? And with what degree

of severity? 

The Marshall Center Web Site:

http://www.marshallcenter.org

Designed and produced by VIB

November 2002