Defense

Reducing the risk of terrorism from seaborne containers is

not just a U.S. border management problem. Once the container

arrives at a U.S. port, it may already be too late to prevent catastrophic consequences. Nor is maritime interdiction of suspicious

cargo an optimal approach due to both the practical problem of

sorting through thousands of stacked containers and the massive

economic disincentives associated with diverting or inspecting

cargo once loaded aboard ship. The primary objective must be to

establish a high degree of confidence that containers earmarked

for U.S. destinations are secure before they leave a foreign port.

The first and most important line of defense against container

terrorism, therefore, is at the foreign point of origin. U.S. control

over cargo bound for American shores should begin there, creating, in effect, a virtual border. This virtual border must be

designed to provide a multilayered defense, addressing container

security from the initial loading of the container to its movement

through the entire international transportation network.

Implementation of a virtual border security program, however, must maintain the economic viability of seaborne commerce.

Security planners must determine how best to construct a security system that substantially reduces the threat from container

terrorism yet still guarantees an uninterrupted flow of trade

goods. Likewise, the right balance must be struck between implementation cost and mitigation of risk. This is a multifaceted problem involving a mix of security, economic, technological, and foreign policy considerations, and any solution will require a

comprehensive, integrated, and international approach.

Overview

America’s potential vulnerability to terrorist attack through

exploitation of the global trade and transportation system is now

widely recognized. The sheer magnitude and diversity of this

global system coupled with the permeability of U.S. borders

afford numerous avenues to attack American targets. Maritime

commerce, and container shipping in particular, provides a highly

attractive means not only of delivering weapons but also of smuggling terrorists themselves into the American homeland. Thousands of ships from every part of the globe deliver millions of individual containers to American ports each year. Compounding the

problem is an inspection process that has been slow to shift from

more traditional practices, such as the search for illegal narcotics, to the search for terrorist weapons. This situation stems

in part from a lack of information specifying cargo contents, complicating U.S. Customs Service efforts to identify high-risk containers for inspection upon arrival, and from the commercially

driven need to move trade goods rapidly through the transportation system. The problem does not end at the American shoreline,

however. The intermodal transportation network, encompassing

sea, land, and rail linkages, represents a vast conduit that could

be exploited for an attack on not only port facilities and marine

terminals but also inland population centers and shore infrastructure. By using global positioning system technology, terrorists may achieve precision targeting capabilities and create a

“poor man’s” intercontinental ballistic missile from a container.

The Virtual Border: Countering

Seaborne Container Terrorism

by Hans Binnendijk, Leigh C. Caraher, Timothy Coffey, and H. Scott Wynfield

Center for Technology and National Security Policy

The National Defense University (NDU) established the Center for Technology and National Security Policy in June 2001 to study the implications of technological

innovation for U.S. national security policy and military planning. The center combines scientific and technical assessments with analyses of current strategic and

defense policy issues. Its major initial areas of focus include: (1) technologies and concepts that encourage and/or enable the transformation of the Armed Forces, 

(2) developments by defense laboratories, (3) investments in research, development, and acquisition and improvements to their processes, (4) relationships among

the Department of Defense, the industrial sector, and academe, and (5) social science techniques that enhance the detection and prevention of conflict. The staff is

led by two senior analysts who hold the Roosevelt Chair of National Security Policy and the Edison Chair of Science and Technology and who can call on the expertise

of the NDU community and colleagues at institutions nationwide. The papers published in the Defense Horizons series present key research and analysis conducted

by the center and its associate members.

A publication of the

Center for Technology and National Security Policy

National Defense University

AUGUST 2002

Number 16

Horizons

August 2002 Defense Horizons 1
Establishment of a virtual border security program requires

improvements in three key areas of container shipping: cargo certification, physical security, and inspection. Procedures such as use of

trusted foreign shippers will establish a higher degree of confidence

that only legitimate cargos are loaded for container shipping, and

utilization of better container seals coupled with improved security

at port and container storage facilities will help prevent terrorists

from gaining easy access to cargo and containers. More sophisticated

container inspection techniques will

require timely and accurate information on individual container shipments

and the introduction of container profiling based on comprehensive data collection and analysis. Receiving detailed

data before a cargo is shipped and analyzing this data by fusing it with data

from other commercial and intelligence sources will enable rapid identification of suspicious shipments. In addition, better detection technology is needed to complement the inspection process.

All of these improvements will require a high level of both

domestic and international cooperation. On the domestic front, the

U.S. Government, working in concert with the business community,

needs to develop a comprehensive national strategy. Key components of this strategy must include the delineation of clear lines of

interagency authority and responsibility and the identification of

additional legislative changes that might be necessary to bolster the

security of commercial practices in economically sound ways. On the

international front, exporting states need to assume greater responsibility for container shipping security. Diplomatic initiatives will be

required to establish agreements on intelligence sharing, container

security standards, and global shipping practices. Despite the

numerous vulnerabilities associated with container shipping and the

seeming intractability of the problem, an international program

based on the concept of the virtual border can substantially reduce

the risk from seaborne container terrorism.

Background

In October 2001, the Center for Technology and National

Security Policy (CTNSP) initiated an independent, unclassified

study to address the potential terrorist threat posed by seaborne

container shipping. Participants included a multidisciplinary team

of specialists drawn from the technology, policy, and transportation

communities within the National Defense University and other government and private organizations.1 The purpose of the study was to

analyze the characteristics of the container threat and suggest ways

in which the security of seaborne container shipping might be

improved, particularly through the use of detector technologies. The

study focused on the seaborne importation of containers into the

United States, although it was recognized that U.S.-exported containers and containers entering the country through air and land

routes present similar threats. Participants also acknowledged that container

security is truly an international problem and that a terrorist attack anywhere within the international trading

system would have an adverse effect

upon the system worldwide.

To inform the policy debate, the

findings of the study were presented earlier this year as a series of briefings to

personnel representing agencies involved in various aspects of maritime and transportation security. This article summarizes the findings of the study and subsequent CTNSP research.

The Seaborne Container Threat

The a priori assumption of America’s vulnerability to terrorist

attack via seaborne container shipping was based on the nature of the

global container shipping industry. The numbers of containers entering the United States, the manner in which these containers move

through the international transportation system, and the weaknesses

in container documentation and inspection processes all contribute to

the attraction of containers as terrorist weapons. World Shipping

Council estimates underscore the magnitude of the potential problem:

approximately 800 oceangoing liners and their multinational crews

make more than 22,000 port calls in the United States each year. Consisting primarily of container ships and roll-on/roll-off vessels, these

liners from every part of the globe deliver to the United States approximately 7.8 million containers of imported cargo per year—an average

of 20,000 containers per day—and these numbers are growing dramatically.2 At the Los Angeles-Long Beach port complex, for example,

one of the Nation’s largest and busiest port facilities, officials estimate

that port traffic will double over the next 2 decades. The planned milelong wharfs will accommodate up to six new generation cargo vessels

with the capacity to carry as many as 15,000 containers. Dozens of

computerized cranes will offload these containers onto endless lines

of waiting 18-wheelers and hundreds of trains.3

The container industry is a remarkably efficient commercial

system, designed to move goods through the international marketplace in the most expeditious manner, but it is not an industry

designed for security. Speed and cost are the overriding drivers in

this system. There are no economic incentives either to perform

cargo inspections or to generate paperwork beyond what is essential

to move containers through the various stages of shipping. The huge

volume of container traffic and the usually lax controls over cargo

packing and shipping provide ample opportunities to introduce a

2 Defense Horizons August 2002

Hans Binnendijk holds the Roosevelt Chair of National Security Studies and is

the Director of the Center for Technology and National Security Policy (CTNSP)

at the National Defense University. Dr. Binnendijk may be contacted at 

(202) 685–2557 or via e-mail at binnendijkh@ndu. Leigh C. Caraher is a 

research analyst at CTNSP, and may be contacted at (202) 685–2659 or via e-mail

at caraherl@ndu.edu.Timothy Coffey holds the Edison Chair of Science and

Technology at CTNSP, and is a senior research scientist at the University of

Maryland. Dr. Coffey may be reached at (202) 685–2658 or via e-mail at

coffeyt@ndu.edu. H. Scott Wynfield is a research fellow at CTNSP, where he 

may be contacted at (202) 685–2530 or via e-mail at wynfieldh@ndu.edu.

a terrorist attack anywhere

within the international

trading system would have

an adverse effect upon the

system worldwide
weapon into a container at several stages in the transportation

process. The increasing magnitude and speed of this trade is already

sufficient to overwhelm existing inspection processes. Unless

changes are introduced, a weapon probably could arrive at a U.S.

port undetected.

While an attack on an American port would yield serious consequences, the threat is not restricted to ports alone; inland sites are

equally at risk. From the port of entry, containers enter a vast transportation network of truck, rail, and inland waterway routes over

which they are delivered to American addresses or carried in bond en

route to international destinations. Several thousand containers

move along major transportation arteries throughout the U.S. mainland daily, exposing numerous urban centers and facilities such as

nuclear power plants, chemical and oil refineries, hazardous material

storage sites, and key transportation infrastructure to attack. Along the Houston Ship

Channel, for example, there are 150 such

sites that might be vulnerable.4

Using simple mechanical triggering

devices or more sophisticated technology

based on the global positioning system

(GPS), for instance, a weapon-carrying

container may be readily transformed into

a precision-guided munition. Using such

technology, several containers, perhaps

arriving on opposite coasts, might be configured to attack selected targets in different parts of the country

with near simultaneity. An attack on this scale has the potential to

cause devastating loss of life in addition to perhaps billions of dollars

in damage to the U.S. economy. Furthermore, the massive economic

disruption that would be created by such an event, particularly in

this era of increasing global reliance on seaborne commerce, might

effectively shut down global trade for a prolonged period of time.

To assess the threat from a terrorist attack utilizing a container

imported into the United States, the study team posited several

operational scenarios. The objective of this approach was to characterize the most immediate risks to suggest appropriate near-term

countermeasures, particularly the use of detector technologies. Two

operational scenarios were considered probable. First, the weapon

could be placed in the container at an overseas loading point, and

terrorists could mask the contents by making the shipment appear

to be legitimate. Second, the weapon could be introduced surreptitiously into a legitimate container shipment somewhere along the

transportation route. In both cases, the weapon might be designed

either to detonate at a specific point along the route or to be

retrieved by an agent for subsequent use. The study team recognized

that weapons could be obtained or assembled domestically and

placed in a shipping container for export. This scenario was not

examined in detail because the study focused on the threat of

imported containers.

The characteristics of a specific container threat are based on

the type of weapon that might be employed, the probability that terrorists would have access to their weapon of choice, and the likelihood of using a seaborne container as the means of delivery. The container itself seems ideally suited for mounting a terrorist attack. The

abundant cargo space of the international standard 8-foot-by-8-foot

container, which ranges in length from 20 to 48 feet, affords a convenient vehicle to convey both large devices, in which the container

itself may be part of the weapon, and small, concealed devices,

intended for receipt and use by an agent in country.5 Thus, nuclear,

radiological, and large conventional explosive devices could be

employed as well as chemical, biological, or smaller conventional

devices. The arrest by Italian police of an Egyptian man in a wellprovisioned container in October 2001 demonstrates that containers

might also be used to transport terrorists themselves.

From the range of possibilities, the study team concluded that

containers carrying a radiological bomb or Stinger-like antiaircraft

missile represent the most significant near-term threats. In both

cases, a seaborne container was judged an ideal mode of transportation, while utilization of either device had the potential to cause

large-scale loss of life and create substantial economic disruption. In the case of a

radiological weapon, it was deemed probable that the radioactive material and chemical explosives needed to construct a “dirty

bomb” could be obtained from foreign

sources, and the device could be shipped by

container from a different country.6 Similarly, the relatively small Stinger missile

could easily be smuggled in a container.

The Taliban are believed to have an

unknown number of American-supplied

Stinger missiles left over from the war against the Soviet Union, and

they may have obtained more from other international sources.

Although this assessment highlights radiological devices and

Stinger-like missiles as probable weapons, other weapons may also

be employed in a seaborne container (though this is relatively less

probable in the near term). A nuclear weapon would certainly produce the greatest destruction, but terrorist possession of such a

weapon was deemed less probable at the time of the study. Also, if

one were acquired, it might prove too valuable an asset to relinquish

control over it by shipping in a container. In the case of biological

weapons, the smaller size of the weapon containers makes such

devices readily transportable by means other than a container. Since

containers are routinely used to ship chemicals, the study team

believed conventional explosives might be utilized in conjunction

with legitimate chemical shipments to magnify the destructive effect

of the explosion. Stand-alone conventional explosives, similar to the

fertilizer bomb used in Oklahoma City, could also be employed, but

because a weapon of this type could be assembled domestically, an

imported container may be a less likely source of transport. While

these conclusions represent the team’s assessment of the relative

threat at the time of this study, the threat is likely to evolve significantly as particular weapons become more available and as terrorists

adapt to new security measures designed to prevent the use of containers as transport vehicles.

The Container Domain

When an American buyer creates a typical purchase order for

goods from a foreign seller, an elaborate process involving multiple

parties is set in motion. In addition to the original importer and

August 2002 Defense Horizons 3

containers carrying 

a radiological bomb or

Stinger-like antiaircraft

missile represent 

the most significant 

near-term threats
exporter, financial and insurance institutions, inland transporters,

freight consolidators, dockworkers, ocean carriers, and several government agencies are involved. A typical trade may generate 30 to 40

documents with scores of data elements, many of which involve a

manual exchange of information. In the United States alone, these

transactions involve numerous commercial entities: approximately

400,000 importing and exporting companies, 4,000 licensed forwarders and customs brokers, several thousand consolidators, and

countless freight haulers. On a global basis, several million individuals are engaged in some stage of the container transportation industry.7 The full scope of this shipping process must be addressed to

build an effective response to the container threat. Figure 1 illustrates five key stages in the container transportation domain, each

having unique characteristics that must be addressed in constructing a comprehensive security plan.8

From a counterterrorism perspective, the most critical stage in

this process involves the initial transactions between buyer and

seller, including generation of the initial shipping documents, loading and sealing of the container, and its delivery to the exporting

port. In current commercial practice, individuals or companies may

order, load, and seal a container, providing only scant detail on the

contents and ownership of the cargo. In some instances, container

cargo is shipped through inland consolidators, where a number of

smaller orders may be combined to produce a full container load. In

this transit phase, suppliers, packers, freight consolidators, and

transporters will handle the cargo and container box. Such business

practices make it more difficult to know precisely the contents of a

particular container and the true identity of the original shipper.

Once a container is sealed and enters the transportation system, the security problem is further exacerbated because the container is not secured as it moves through the system. As a result, the

4 Defense Horizons August 2002

Figure 1. The Container Domain

*Documents reported to U.S. Customs Service

Key Stages Process Step Source of Data

Days to 

Arrival

40

25

21

5

4

0

Fluid time frame

STAGE 2

STAGE 3

STAGE 4

STAGE 5

STAGE 1

Border Today

Seller generates documents

 ● Shippers letter of instruction

 ● Commercial invoice*

Forwarder/consolidator 

generates documents

 ● House bill of lading

Carrier generates documents

 ● Master bill of lading*

Customs broker and/or shipper 

reporting

 ● Customs form 7501 and 3461*

Additional carrier reporting

 ● Shipment status

 ● Vessel manifest*

Additional documents may finally 

be received here

 ● Surface bill of lading

Buyer generates purchase

 ● Purchase order

Seller and buyer 

agree

One or more consolidation 

layers mask goods’ origins 

and involved parties (40%)

Carriers accept containers 

from multiple sources, 

with only partial data on 

contents and origins

Earliest possible filing 

of U.S. Customs entry 

information (ABI)

Ship manifest information 

must be filed by 4 days 

prior to arrival (AMS)

U.S. Customs applies 

physical and commercial 

border in port zones

Sellers

Inland 

consolidation 

warehouse

Foreign port 

of voyage 

origin

Voyage 

underway

Carrier 

reporting

First U.S. 

destination 

port

Buyers
integrity of the container box is subject to compromise, particularly

after it arrives at a foreign port for the second stage of its journey.

Here a number of factors contribute to the problem. The absence of

stringent sealing requirements for container boxes, lax physical

security, and minimal inspection at some foreign ports, coupled with

limited U.S. oversight at these ports, all create security risks. A similar problem exists once the vessel is under way and the ship’s crew

and passengers and workers at port stops come into contact with the

containers along the ship’s route of transit. The fact that U.S. Customs Service inspectors routinely find broken seals on containers,

most likely opened to pilfer the contents, indicates vulnerability to

tampering after initial loading.

Since the current Customs system was designed primarily for

economic protection, shipping documentation requirements are

structured to provide information related to commerce. With the

exception of hazardous material, exporters may not report to the carrier the exact contents of the cargo, and

the information that shippers provide is

often intentionally misleading, designed

to protect forwarders from competition

by carriers, to avoid tariffs, or to protect

the cargo from theft.9 Even when there is

no attempt to obfuscate, the cargo shipping information is often neither accurate and complete nor timely enough to

allow for effective screening to identify

potential terrorist threats. As figure 1

illustrates, much of the data is reported

after the ship is under way or even after its arrival in the United

States. Documents such as the commercial invoice and master bill of

lading normally provided to U.S. Customs inspectors consist of only

that information necessary to ensure compliance with Customs rules

and tariff requirements.

Once a shipment arrives at a U.S. port, Customs inspectors are

faced with the problem of determining which containers among the

thousands to inspect. Under current procedures, approximately 2

percent of containers are selected for inspection to ensure compliance with U.S. laws governing importations, to determine appropriate entry of restricted merchandise such as hazardous material,

and to intercept prohibited items such as narcotics and other contraband. Transiting the country en route to other foreign destinations, containers shipped under a customs bond are often subject

to even less scrutiny.10 While counterterrorism is now a priority

within U.S. Customs, adequate procedures for inspection have not

yet been implemented.

Although the current percentage of containers inspected upon

entering the country may appear small, determining if this figure

represents the “right” containers is more important than the actual

number of containers inspected. To make this determination, the

U.S. Government needs substantially better visibility into the entire

container domain, particularly the first stage in the shipping

process. It is important both to verify the specific contents of a cargo

and to establish the identity of the shipper prior to container loading. If this verification does not take place, a more stringent mechanism for inspecting the container is required. Simply speaking, it is

necessary to push the U.S. border back to create a virtual border in

the country of origin to establish a high degree of confidence that

container cargo bound for American shores is safe. Security initiatives, however, must not end at the port of embarkation. The concept

of a virtual border implies not simply a fixed line at the foreign

shoreline but rather a multilayered defense for the end-to-end movement of cargo throughout the container domain.

Shoring Up the System

Creating an effective virtual border security program requires

improvements in three essential areas: creating an initial certification process; enhancing the physical security of the standard shipping container; and creating a more sophisticated inspection system

using container profiling and better detection technology.

A fundamental goal of the virtual border approach is to establish a certified cargo in which a container’s contents are well documented, verified, and approved prior to

shipping to the United States. Accomplishing this entails establishment of

minimum data requirements and a

tighter reporting timeline for commercial documentation. The sources of data

shown in figure 1 might be combined

with other commercial documents, such

as financial data and inland transportation information, to provide a complete

picture of the transaction, the parties

involved, and the transportation plan.

Prescreening of cargo will allow Customs to authorize shipment to

the United States before loading rather than waiting until the shipment is under way, as in current practice. Creating a new electronic

security questionnaire enabling rapid, automated screening and certification of container cargo would expedite this process and minimize costly delays. To facilitate the certification process, the Customs Service will need to station its officials at overseas ports.

Shippers complying with physical security requirements for

containers and participating in this electronic inspection and certification process would be designated trusted agents. They might

receive economic incentives through the use of “green lane” passes

designed to expedite their shipments through the maritime system.

Such rewards might be balanced by penalties. Shippers who are

unable or unwilling to comply might find their shipments delayed

until physical inspection of the contents can be completed. Rather

than utilizing simple go or no-go criteria for cargo certification, a

ranking system could be employed that would assign levels of risk for

each container. Such a ranking system could also be useful in allocating limited inspection resources.

A second objective is to ensure that contents remain secure by

enhancing the physical security of the container itself, which

requires improvements in both the integrity of the container box

and the environment in which it moves, particularly the port facility. Physical security must begin at loading with the use of international standard, registered, and tamper-resistant container seals,

August 2002 Defense Horizons 5

the U.S. Government needs

substantially better

visibility into the entire

container domain,

particularly the first stage

in the shipping process
and inclusion of seal numbers on all shipping documentation. The

integrity and serial number of the seal could be checked as the container passes to different parties in the transportation process.

Broken or missing seals would constitute cause to refuse acceptance. If the container must be opened for any reason, a new seal

would need to be affixed and the new seal number recorded in the

container documentation.

Proposals for electronic sealing, sensing devices inside a container to indicate tampering, and utilizing GPS-based technology to

provide precise container location information have been suggested.

While such devices would contribute to the physical security of the

container box, the implementation of these devices in the near term

might prove both impractical and prohibitively expensive, given the

millions of containers in the international system. More research is

therefore needed to determine the optimal future approach to economically ensuring container integrity.

As important as proper sealing is protecting the container from

unauthorized access while in port or in a storage facility. To ensure

that access is restricted to authorized personnel and vehicles, international minimum standards for marine terminal security should be

established. These standards might include requirements to establish port security plans and to credential certain types of port workers. In areas where containers are stored temporarily, attention must

be given to adequate fencing, lighting, and access control points.

Sufficient numbers of trained security personnel also are needed to

conduct routine monitoring and inspections of container shipments.

Improving the completeness and timeliness of container cargo

information and protecting the container itself are only part of the

solution. Creating a more sophisticated inspection process will

require individual container profiling, a continuous process that

begins with the initial certification of the cargo and continues until

the container arrives at an American port. Profiling entails the collection and analysis of not only the commercial data supplied by shippers, ocean carriers, and third parties but also national security and

law enforcement information. When this broad range of information

is combined at a fusion center (shown notionally in figure 2), a more

comprehensive security assessment of containers, ships, and crews

can be created. Container profiling based on this national-level analysis will make it easier to identify with greater precision suspicious

cargos that could be held at a foreign

pier or interdicted under way.

The operation of the fusion center is inherently a government-wide

responsibility dependent on allsource information and a high level

of cooperation among numerous U.S.

Government agencies. Many information and data collection systems that

could provide input to the fusion center already exist or are under development within agencies responsible for various aspects of the container problem. For example, the

Customs Automated Commercial Environment and the International

Trade Data System (a multiagency effort) currently under development promise significant improvements in capturing the data necessary to profile containers.

To ensure a systematic and integrated approach to the development of these and other data collection systems for container profiling, an interagency architecture is required. Among the first steps

toward establishment of the fusion center must be a review of existing agency information systems, a determination of data requirements for container profiling, and the development of a plan to integrate these systems. Operational

and technical architectures specifying standard data reporting formats

and secure interagency communications links are needed before a realtime, accessible container database

can be created.

The development of new data

analysis methodologies and advanced

computational techniques will optimize the fusion center’s product. This will require establishing rule

sets to recognize the relationships between disparate pieces of information and to identify certain patterns or discrepancies. Risk assessment algorithms may then be created based on current understanding

of the shipping industry to identify anomalies in the shipping process.

Anomalies that could be targeted include document discrepancies,

cargo incongruous with its origin, suspicious parties involved in the

6 Defense Horizons August 2002

improving the completeness

and timeliness of container

cargo information and

protecting the container itself

are only part of the solution

Figure 2. Fusion Center

Ocean 

Carriers

• Master bill 

• Vessel manifest

Shipper 

• Letter of instruction 

• Commercial invoice 

• Certificate of origin

• Packing list

Third Parties 

• House bill of lading 

• Financial data 

• Inland transport data

Commercial

Profile

U.S. Government

Profile

Fusion

Center

National Security 

• National intelligence 

 agencies

• Department of State

Law Enforcement 

• Federal Bureau of Investigation

• Immigration and Naturalization Service

• Coast Guard

• U.S. Customs Service, etc.
transaction, suspect routing or shipping prioritization, and any other

contradiction or violation of commercial shipping practices.

Analyzing all-source data in new ways may also provide wholly

new insights into potential threats. When commercial data pertaining to an otherwise innocuous cargo, perhaps precertified as safe, is

combined with vessel tracking information, crew lists, and a report

of a probable terrorist presence in a port of call, red flag indicators

would be triggered, even though

any of these individual events

would have been insufficient to

produce a warning.

Even more sophisticated

analysis may be achieved with

advanced computational techniques in which the fusion center’s meta-database is combined

with anticipatory or predictive

models and search strategies. By

providing quantitative and qualitative insights into the complex

behavior of terrorist organizations, agent-based modeling and simulation, or artificial neural networks, could generate new pattern recognition algorithms, which in

turn would shape new search strategies and produce new risk

assessment programs. In anticipation of evolving threats, in which

terrorists seek to mask behavioral patterns that would identify their

actions, evolutionary analysis may provide an effective means of discovering such patterns. These evolutionary, or genetic, algorithms

would be used to develop offensive strategies potentially used by terrorists and to suggest defensive counterstrategies. The combination

of a meta-database and anticipatory modeling would enable the

fusion center to identify current container threats better and anticipate probable future threats as terrorists adapt to our defenses.

The Role of Detectors

Improvements in the inspection process through container profiling can be further enhanced by the use of sophisticated detection

devices capable of identifying nuclear weapons, radiological materials,

chemical and biological agents, and conventional explosives. Employing these devices at ports of embarkation, where containers are loaded

onto vessels, is an important element in creating a virtual border.

If a terrorist container does enter

an American seaport, these countermeasures would also provide

the final line of defense. Therefore, this study undertook an initial survey of detector technologies. The survey was restricted to

unclassified literature and

focused on available detector

technologies rather than providing a comprehensive assessment

of their potential applications. The intent was to examine technologies suitable for use on closed containers in a port environment where

speed, ease of use, and low false alarm rates are critical.

Nuclear Material Detection

In the case of a nuclear weapon, the principal interest is in the

detection of gamma radiation and/or neutrons emitted as a result of

spontaneous fission or some stimulation process. In the case of radiological weapons, it is the detection of gamma radiation. (Table 1

provides a summary of several relevant technologies.) One of the

best understood passive detectors for nuclear radiation is the

sodium iodide crystal coupled with a photomultiplier tube. The

detection range for weapons-grade quantities of fissile materials,

August 2002 Defense Horizons 7

the inspection process can 

be further enhanced by the use 

of sophisticated detection devices

capable of identifying nuclear

weapons, radiological materials,

chemical and biological agents,

and conventional explosives

Table 1. Nuclear Detection

Type Technology Size Characteristics

Passive gamma ray Sodium iodide crystals and 3-inch crystals Robust, high false alarm rate at high sensitivity,

photomultiplier tube poor spectral resolution

Passive gamma ray Germanium 3-inch crystals Sophisticated instrument, needs refrigeration, very high

resolution (does not make mistakes)

Passive gamma ray Mercuric iodide Few square inches Intermediate spectral resolution, solid-state, robust,

relatively expensive

Passive neutron Scintillating glass fibers 100 square inches Robust, solidstate, wound to desired geometry

Passive solidstate neutron CMOS/SOI* Small (like cell phones) Relatively inexpensive, small, no real database on utility

in real world

Geiger counters Simple ionization chamber Hand-held Not specific, low sensitivity, relatively inexpensive

Active neutron interrogation Pulsed neutron source Large Sophisticated instrument, radiation hazard

Active gamma ray scanner Pulse power Large Robust technology, radiation hazard, good spatial

resolution, imaging

*Complementary metal oxide semiconductor/silicon on insulator
which is small on land due to the interference of natural background

radiation, improves slightly over water. The relatively compact

sodium iodide system tends to have a high false alarm rate when

operated at high sensitivity and has poor spectral resolution of the

gamma ray radiation being measured.

A second class of well-understood gamma radiation detectors is

made from high-purity germanium crystals. These crystals are typically similar in size and detection ranges to the sodium iodide crystals. The high-purity germanium system has a very high spectral resolution for the gamma radiation being measured and generally does

not make a mistake in identifying the device responsible for the

gamma radiation. However, this system is quite sophisticated and

requires refrigeration. Compact versions of these detectors are now

being produced.

A relative newcomer in nuclear gamma radiation detection is

the mercuric iodide detector. This detector has a spectral resolution

between that of sodium iodide and high-purity germanium. It has the

advantages of being an all-solid-state system and requiring no refrigeration. However, it is relatively expensive when produced in the size

that would be needed for the port application.

The classic detector for neutrons produced as a result of spontaneous fission is the Helium-3 gas proportional counter. These devices are well

understood and tend to be relatively bulky.

The detection ranges for neutrons are similar to those for gamma radiation. In

recent years, specially treated glass fibers

have been produced and commercialized

for the purpose of neutron detection. This

technology has the distinct advantage of

being able to be wound so as to produce

specific geometric shapes that might be advantageous for neutron

detection. A typical panel for a neutron detector built from these

classes of fibers might be about 100 square inches in size. These

devices also have the advantage of being all solid-state.

Unlike previously mentioned detectors, complementary metal

oxide semiconductor/silicon on insulator (CMOS/SOI) technology

with special dopants is not currently available; however, its development may enable commercial cellular telephone technology to be

exploited for the production of inexpensive mass-produced thermal

neutron detectors. One could envision combining such technology

with tracking technology based on GPS so that one could monitor the

neutron state of a given container as it moved around the world. This

type of technology might have further application as a general detector for use throughout the U.S. infrastructure. While the technology

appears promising, there is no database on its actual utility in real

world applications.

There are also active techniques for penetrating a shipping

container in an effort to find nuclear materials. One example of this

is the pulsed neutron source. A high-energy neutron produced, for

example, from the D–T reaction is fired into the shipping container

to interact through inelastic scattering with the elements in the

material under investigation. Gamma radiation would be searched

for to see if the radiation characteristic of a particular material is

detected. These devices are relatively large and would be suitable

only in a port environment. The devices and the interpretation of the

signatures measured require a high degree of sophistication. It

should be noted that this approach has application to detection of

materials other than nuclear materials, for example, for nitrogen in

conventional explosives.

Another active detection device is the gamma ray scanner, a

large device intended to image the inside of the shipping container.

It is quite well understood and might form the backbone of any port

container inspection system.

Explosive Detection

Explosive detection systems generally fall into two categories:

bulk detection and vapor phase detection. Several of the techniques

typically utilized in each of these detection categories are listed in

table 2. The gamma ray imagers and pulsed neutron detectors were

mentioned in the discussion of nuclear materials detection. Both

nuclear magnetic resonance and nuclear quadrupole resonance are

techniques that will not detect explosives through metallic containers and are therefore not suitable for the rapid screening of shipping

containers. Use of a vapor phase detector,

which works off the natural vapor pressure associated with explosives, would

most likely involve extracting an air sample from a closed shipping container and

examining the sample. The vapor pressure of explosives varies over quite a

wide range. For example, when compared

with the concentration of molecules in

air, the vapor pressures of EGDN, DNT,

and NG fall in the range of parts per million. However, the vapor

pressures for ammonium nitrate and TNT fall in the range of parts

per billion. The modern explosives RDX, PETN, and HMX have

vapor pressures in the range of parts per trillion. Table 3 provides

the practical detection capabilities of the various vapor detectors

listed in table 2. Since the vapor pressure represents the maximum

vapor concentrations that could exist in the closed container, it is

clear from table 3 that detection of explosives through the vapor

pressure technique will be difficult in the near term. However, there

have been promising developments.11

Chemical and Biological Detection

Technologies used for the detection of chemical agents in a

container will probably be similar to those for the detection of

8 Defense Horizons August 2002

there are also active 

techniques for 

penetrating a shipping

container in an effort 

to find nuclear materials

Table 2. Examples of Explosive Detectors

Bulk Detectors Vapor Detectors

Gamma ray and X-ray Ion mobility spectrometry

Neutron (thermal, fast, pulsed fast) Gas chromatography

Nuclear magnetic resonance (NMR) Chemiresistor

Nuclear quadrupole resonance (NQR) Fluorescent polymer
explosives. Chemical agents, such as nerve agents, typically have

rather high vapor pressures ranging from a few thousandths of an

atmosphere for Sarin to a millionth of an atmosphere for VX. If a

container holding a nerve agent is leaking, the vapor phase detectors discussed previously very likely would provide a detection. The

design of weaponized chemical agent

containers, however, precludes leaking. Therefore, it is unlikely that militarized chemical agents would be

detected using these technologies.

The detection of biological agents

shipped in seaborne containers presents the most difficult problem. Since

biological agents have no vapor pressure and in all likelihood would be

shipped in small quantity and therefore

be well hidden, current detector technology probably would be ineffective. 

The immediate deployment of gamma ray imaging technology

and other current detectors to address the threat from radiological

weapons is recommended. A gamma ray imager might also be developed along with other existing technologies to create a single point,

multipurpose detector. The imager would provide a degree of visual

inspection capability to examine the contents of the shipping container that could be supplemented with one or more of the nuclear

detection technologies mentioned above. If an air sample could be

drawn from the container, it would be possible to test for chemical

agents and explosive vapors. However, for the reasons stated above,

detection seems unlikely.

One of the most important questions regarding detectors is

how best to employ a particular technology. The study recognized

the importance of introducing technological screening devices that

could be incorporated into the container transportation process in

a nonintrusive manner at both the ports of origin and destination.

To minimize costly delays, the detector must be capable of sampling individual containers without unduly interrupting their

movement between the ship and various land transport systems.

Detectors currently in use or proposed for development might be

employed in four ways: detectors incorporated into devices used to

handle the container box; fixed, pass-through detectors that scan

containers as they move through or near the device; mobile detectors ranging from hand-held to truck-mounted devices; and detectors incorporated into the container

box. For example, proposals exist to

incorporate detection systems into the

cranes that lift containers between

the ship and pier or to pass containers

through scanning devices by truck or

rail. Further research will be needed

to determine which detector or combination of detectors will prove most

cost effective.

For the long term, it is quite clear

that a substantial program is needed to

move promising detection technology

from the laboratory to the port. An important first step toward establishing a port detector program is to create a technology investment

plan that would identify promising areas of research and help prioritize investments. A technology investment plan might also be used

to coordinate science and technology resources among government

agencies developing detectors and to optimize investment expenditures by eliminating duplication of effort among these agencies.

Creating the Virtual Border

Assembling the pieces of an effective virtual border strategy

will require a great deal of coordination and cooperation among the

responsible parties involved, both domestically and internationally.

If the virtual border concept is to work, a unified, international program must take into account not just the cross-cutting lines of

responsibility and authority of the U.S. interagency process but also

the economic realities of the commercial trade industry and the

interests of our international trading partners. Part of the challenge

in constructing a virtual border program is the issue of cost versus

risk. Where do we find the funding for this program? How many dollars should be spent, and what is the fair proportion of these expenditures between the U.S. Government and our overseas partners?

How do we measure the effectiveness of the program?

August 2002 Defense Horizons 9

an effective virtual border

strategy will require a

great deal of coordination

and cooperation among the

responsible parties

involved, both domestically

and internationally

Table 3. Comparison of Vapor Pressure Detection

System Detection Limits Limitations

Ion mobility spectrometer Parts/billion Must be close to explosive or chemical, noise limits become problems at low signal levels,

fundamental problems in selectivity and resolution, shows promise for increased detectioin in 

low concentration

Chemical resistors Parts/billion Must be close to explosive or chemical, needs improved signal-to-noise ratio (SNR)

Fluorescent polymers Parts/trillion Must be close to explosive or chemical, needs improved SNR, demonstrated at parts/billion

(in principle) in reliable system

Gas chromatography + Parts/billion Must be close to explosive or chemical, must be able to desorb the explosive vapors for

sound acoustic wave system to be useful
Currently, no single U.S. Government agency has final accountability for seaborne container security. In fact, the Customs Service,

Coast Guard, agencies within the Departments of Transportation,

Commerce, and Agriculture, the Immigration and Naturalization

Service, Maritime Administration, and numerous state and local

entities all have jurisdiction over various parts of container commerce, shipping, and port operations. Recognizing the difficulty of

coordinating across departments, President George W. Bush proposed in June 2002 the creation of a single department whose primary mission is to protect the homeland. The Department of Homeland Security would be charged with, among other responsibilities,

preventing terrorists and explosives from entering the country and

bringing together scientists to develop technologies that detect biological, chemical, and nuclear weapons.12 Under this proposal, the

U.S. Customs Service, Coast Guard, and

Transportation Security Administration

would be reorganized under the new department to increase cooperation and coordination. This new department would provide the

type of coordination needed to enhance container security.

As the U.S. Government moves forward

with the implementation of a container

security program, it must do so in concert

with the business community. Government

and commercial cooperation is necessary to

ensure that proposed security measures are

readily incorporated into existing commercial practices or introduced in such a way as to minimize the disruption to commerce.

Wherever possible, the goal should be to achieve voluntary compliance with new security requirements for container shipping and

port operations.

The virtual border approach requires a high degree of international cooperation. Exporting states need to assume greater responsibility for the security of container shipping originating from or passing through their ports. In the near term, increased cooperation

between the United States and foreign governments will improve

coordination in the collection and sharing of container cargo shipping

information and will heighten physical security at ports and facilities

through which container traffic moves. The United States will also

need to work with its trading partners to facilitate the creation of

trusted shipping agents and, where warranted, to create a more

prominent role for U.S. Customs at foreign ports that might include

more on-site inspectors and detection equipment. Such measures will

likely require reciprocal improvements at U.S. port facilities, including stricter inspection of exported containers and potentially allowing foreign inspectors in U.S. ports. In fact, it is realistic to assume

that our trading partners will expect us to introduce the same measures domestically as those we advocate overseas. In addition to foreign governments, cooperation with international organizations, such

as the International Maritime Organization (IMO) and the World

Customs Organization, will be needed. Some efforts in both organizations are currently under way. Recognizing container terrorism as a

potential international problem, the IMO, for example, recommended

enhanced physical security at port facilities and improved inspection

processes. As security measures are introduced, U.S. security as well

as the security of global trade will likely improve.

Rather than designing a comprehensive container security program for future implementation, the process should be started immediately through an incremental approach similar to spiral development currently used by the Department of Defense for major systems

development. In spiral development, pieces of the system are built

and tested, and improvements are made based on a continuous series

of operational performance evaluations. The nature of container

threats is well enough understood that a similar demonstration program could be constructed for a virtual border prototype. The initial

phase would include identifying shipping elements needed to establish threat profiles, specifying a standard electronic reporting format,

and establishing links between various databases, such as those shown in figure 2. Representing an existing baseline capability, the

National Maritime Intelligence Center in Suitland, Maryland, could serve as the data fusion

center recommended by this study. During its

transition, agreements could be negotiated

with Singapore, Hong Kong, Rotterdam, or one

of the other mega-ports to serve as a prototype

development test site. This spiral development process would also include a continuous

red team evaluation of the most probable

threat scenarios. Red teams will prove to be a

critical element in identifying necessary changes to the baseline system, especially as advanced computational techniques are introduced into the container profiling process.

Moving Ahead

Since the completion of this study, a number of steps toward

the implementation of a virtual border security program have been

taken. An interagency container working group, sponsored by the

Office of Homeland Security, was formed in December 2001. This

group’s recommendations closely mirror the findings of this study in

a number of areas. These include the need for government and business coordination, improving container cargo data collection and

analysis, improving the physical security of containers, working with

our trading partners abroad, and utilizing advanced detector technologies to enhance the inspection process.

10 Defense Horizons August 2002

Defense Horizons is published by the Center for Technology and National Security Policy through the

Publication Directorate of the Institute for National Strategic Studies, National Defense University.

Defense Horizons and other National Defense University publications are available online at

http://www.ndu.edu/inss/press/nduphp.html.

The opinions, conclusions, and recommendations expressed or implied within are those of the

contributors and do not necessarily reflect the views of the Department of Defense or any other

department or agency of the Federal Government.

Center for Technology and National Security Policy

Hans Binnendijk

Director

exporting states need

to assume greater

responsibility for the

security of container

shipping originating

from or passing

through their ports
Legislation under way introduces many of the improvements recommended by this study. The Maritime Transportation Antiterrorism

Act of 2002 calls for the development and maintenance of an antiterrorism cargo identification and screening system and improvements in

the physical security of containers. This legislation also provides for

the electronic submission of containerized cargo information no later

than 24 hours before a cargo is loaded on a vessel and the electronic

reporting of crew and passenger manifests. The Port and Maritime

Security Act of 2001 focuses on port vulnerabilities and ways to

enhance security at port facilities. Though it does not specifically

address physical security of containers, it does call for electronic submission of cargo manifest and crew information, development of nonintrusive screening and detection equipment, credentialing of port

personnel, and improved collection and coordination of maritime

intelligence. These provisions and other proposed improvements similar to the virtual border construct introduce changes that will significantly enhance maritime security.

Over the past few decades, international containerized shipping has evolved to become the main artery of global trade, providing both convenient and inexpensive access to goods from markets

around the world. Yet the very size and efficiencies that have made

container shipping such an attractive means of transport have also

created a system that is highly vulnerable to terrorist exploitation.

Unless fundamental changes in the practices of the current system

are introduced, the possibility of seaborne container terrorism will

remain a significant threat. But proposals to alter current container

shipping business practices must balance security concerns with

economic imperatives, lest global commerce be severely disrupted.

The virtual border proposal seeks to achieve this balance. It

addresses both the need to provide a comprehensive, multilayered

defense against terrorism and to minimize disruptions to the functioning of an orderly international system.

The notion of extending U.S. control over container shipping

beyond our traditional borders that is embodied in the virtual border

concept presents a number of challenges. The timely collection and

analysis of data required for cargo certification and profiling, improvements in the physical security of container shipping, and the development and introduction of sophisticated detection systems, all key elements of the virtual border concept, require an unprecedented level of

domestic and international cooperation. Without such cooperation, no

security program can hope to be effective. It is encouraging to note

that recognition of the potential container problem is now widespread,

and some progress has been achieved. Current U.S. interagency

efforts, pending Federal legislation on maritime security, international discussion, and especially the proposal to create the Department of Homeland Security, are steps in the right direction. Designing

a foolproof system is simply not possible, but if these current efforts

lead to the establishment of a virtual border security program, the risk

of a seaborne container terrorist attack will be substantially reduced.

Notes1 The CTNSP core study team consisted of Hans Binnendijk, Leigh C. Caraher,

Timothy Coffey, and H. Scott Wynfield. Desmond Saunders-Newton provided consultation concerning advanced computing. Col Steven Tomisek, USMC, represented the

National Defense University (NDU) Institute for National Strategic Studies (INSS).

Groups consulted include the U.S. Coast Guard, Customs, Navy, Freight Desk Technologies, Logistics Management Institute, Natural Selections, IBM, World Shipping,

Booz-Allen and Hamilton, and other members of NDU and INSS. 2 Testimony of Christopher Koch, president and CEO of The World Shipping

Council, before the Senate Committee on Commerce, Science and Transportation,

Charleston, SC, February 19, 2002. The World Shipping Council notes that these estimates are based on liner shipping, that is, those vessels operating on regular, scheduled services and fixed routes. Estimates exclude bulk carriers operating for hire on

an as needed, where needed basis. 3 Louis Sahagun, “Really Big Doings at the Ports,” The Los Angeles Times, March

28, 2002. 4 Testimony of Senator Ernest F. Hollings (D–SC), Committee on Government

Affairs, Hearing on Seaport Vulnerability, December 6, 2001. 5 As a basis for comparison, the most common size international standard container, at 40 feet in length, has several times the cargo capacity of the rental truck

used in the 1995 attack on the Alfred E. Murrah Federal Building in Oklahoma City. 6 One potential source for radiological material is the compact radio thermal

generators scattered throughout the former Soviet Union (some of which are now

apparently missing) that contain sufficient quantities of strontium 90 to form the

basis for a dirty bomb. The subsequent capture and interrogation of Abu Zubaydah, a

top bin Laden lieutenant, indicates that al Qaeda may have been trying to develop just

such a weapon. 7 Testimony of Rob Quartel, chairman and CEO, Freight Desk Technologies,

before the Government Affairs Committee of the U.S. Senate, December 6, 2001. 8 The depiction of the container domain in figure 1 is based on an original presentation by Freight Desk Technologies. 9 John Simpson, president of the American Association of Exporters and

Importers, quoted in William Booth, “Where Sea Meets Shore, Scenarios for Terrorists,” The Washington Post, January 3, 2002. 10 The study team’s visit to a large East Coast port confirmed that only modest onsite improvements toward stopping container terrorism have been introduced. Shortages of inspectors and the lack of automated processes hamper counterterrorist efforts. 11 This analysis does not refer to vapor phase detection techniques being applied

to residues of explosives manually collected, for example, by taking swabs. This

approach is simply not practical in the situation envisioned. 12 George W. Bush, address to the Nation on the Department of Homeland

Security, June 6, 2002. 

August 2002 Defense Horizons 11
The DefenseHorizons Series

12 Defense Horizons August 2002

Number 1, June 2001

Managing Change: Capability,

Adaptability, and Transformation

Hans Binnendijk and Richard L. Kugler

Number 2, September 2001

Resurrecting Transformation for the 

Post-Industrial Era

Douglas A. Macgregor

Number 3, October 2001

UCAV Technological, Policy, and

Operational Challenges

Charles L. Barry and Elihu Zimet

Number 4, October 2001

Maritime Access: Do Defenders Hold 

All the Cards?

Arthur H. Barber III and Delwyn L. Gilmore

Number 5, November 2001

Adapting Forces to a New Era: Ten

Transforming Concepts

Hans Binnendijk and Richard L. Kugler

Number 6, December 2001

Current Export Policies: Trick or Treat?

David R. Oliver, Jr.

Number 7, February 2002

Global Trade: America’s Achilles’ Heel

James M. Loy and Robert G. Ross

Number 8, February 2002

Small Security: Nanotechnology and

Future Defense

John L. Petersen and Dennis M. Egan

Number 9, March 2002

Nonlethal Capabilities: Realizing 

the Opportunities

E.R. Bedard

Number 10, March 2002

Rediscovering the Infantry in a Time 

of Transformation

Bing West

Number 11, April 2002

Computer Games and the Military: 

Two Views

J.C. Herz and Michael R. Macedonia

Number 12, April 2002

The Airborne Laser from Theory 

to Reality: An Insider’s Account

Hans Mark

Number 13, May 2002

Relevancy and Risk: The U.S. Army and

Future Combat Systems

Joseph N. Mait and Jon G. Grossman

Number 14, June 2002

Toward Missile Defenses from the Sea

Hans Binnendijk and George Stewart

Number 15, July 2002

Biological Weapons: Toward a Threat

Reduction Strategy

Brad Roberts and Michael Moodie