After the collapse of the Soviet Union, the world's security landscape is said to have undergone a transformation from the seeming stability of the bi-polar balance of power to a system in whichnot only any nation, but sub-national groups as well, may be able to acquire weapons of massdestruction (WMD). Strategies based on containment and deterrence, it is argued, are insufficientto guarantee security in the twenty-first century threat environment; terrorists and "rogue" nationsare not amenable to being deterred or contained. (1) The need to prevent the proliferation of chemical,biological, and nuclear weapons was highlighted in the National Security Strategy of the UnitedStates of America issued in September, 2002. (2) According to the Bush Administration, in order tostrengthen nonproliferation efforts to prevent rogue States and terrorists from acquiring weapons ofmass destruction, [w]e will enhance diplomacy, arms control, multilateral export controls, and threat reduction assistance that impede states and terrorists seeking WMD, andwhen necessary, interdict enabling technologies and materials. (3) Toward that end, President Bush issued his National Strategy to Combat Weapons of MassDestruction in December, 2002. The Administration's plan combines efforts aimed atcounterproliferation, (4) nonproliferation, and WMDconsequence management. Its purported intentis to eliminate or "roll back" WMD from certain states and terrorist groups who possess suchweapons or are close to acquiring them, including potentially the use of force and aggressivemethods of interdiction of WMD-related goods, technologies, and expertise. (5) The use of interdictionas a counterproliferation measure appears to be part of a strategy that foresees the U.S. taking"anticipatory action to defend ourselves" against terrorists and rogue states, "even if uncertaintyremains as to the time and place of the enemy's attack," (6) and "to detect and destroy an adversary'sWMD assets before these weapons are used." (7) A high-profile incident involving the interception of Scud missiles and rocket fuel on board a ship traveling from North Korea in December, 2002, however, illustrated possible legal impedimentsto the strategy. Acting on intelligence from the United States, a Spanish frigate stopped and boardedthe So San , an unmarked North Korean commercial vessel, and discovered the missiles. However,after confirming that the missiles were purchased by Yemen, the United States allowed the vesselto proceed on its voyage. The Bush Administration concluded that there was no legal basis to arrestthe vessel or seize its cargo, because North Korea had not violated any law. (8) In May 2003, President Bush announced a new facet of the WMD strategy, to be known as the Proliferation Security Initiative (PSI). (9) The PSI isan effort to reach agreements among nations toallow searches of ships and aircraft carrying suspected weapons-related cargo. (10) Undersecretary ofState for Arms Control and International Security John Bolton told Congress: The initiative reflects the need for a more dynamic active approach to the global proliferation problem. It envisions partnerships of states working inconcert, employing their national capabilities to develop a broad range of legal, diplomatic,economic, military and other tools to interdict threatening shipments of WMD and missile relatedequipment and technologies. To jump-start this initiative, we have begun working with several close allies and friends to expand our ability to stop and seize suspected WMD transfers.Over time we will extend this partnership as broadly as possible to keep the world's most destructiveweapons away from our shores and out of the hands of our enemies. We aim ultimately, not just toprevent the spread of weapons of mass destruction, but also to eliminate or roll back such weaponsfrom rogue states and terrorist groups that already possess them or are close to doing so. (11) Rather than seeking to change existing treaties or negotiate new ones, the PSI appears to relyon international agreements that will enhance cooperation in interdiction efforts, including sharinginformation and conducting exercises using military or civilian assets to develop the participatingnations' ability to conduct air, ground, and maritime interception. (12) However, recognizing thatcooperation may not always be forthcoming from all nations whose assistance is requested, theAdministration has intimated that it will act unilaterally, if necessary. (13) These developments raise questions related to the international law of jurisdiction. International law outlines the bounds of the permissible conduct for purposes of self-defense and law enforcementactivities abroad, insofar as some activities could be viewed as unwarranted or unlawful interferencewith the rights of other nations to conduct international commerce and maintain sovereignty overtheir territory. This report provides an overview of the international law of the sea as it relates to thepermissible range of methods for interdicting WMD-related contraband on the sea and in the air, andalso of selected pertinent international regimes and agreements. After a short outline of the currentlegal regime for the international control of WMD, the report outlines the basic concepts ofjurisdiction in international law. Next, the report describes concepts central to the law of the sea,the rights and limitations. The report then turns to the international legal framework limiting theconduct of nations as it applies during times of war and peace, as well as during what might be called"quasi war," as is often deemed to be the case today. From a U.S. perspective, the problem of controlling the proliferation of WMD is particularlythorny because, unlike the control of illicit drugs, it does not suffice to keep the materials fromentering the United States or to prevent their manufacture and dispersal on U.S. territory. Completesecurity from the dangers of a WMD attack would require that dangerous materials be kept out ofthe hands of any potential enemy. Moreover, some materials that can be used in the production ofWMD also have peaceful uses, and may even be necessary for the operation of wholly legitimateindustries. Interference in the trade of "dual use" materials could impair the ability of other Statesto carry out legitimate trade, possibly leading to international discord. Finally, under internationallaw, sovereign States have the right in general to possess weapons for their self-defense. Only theuse of such weapons is constricted by customary international law. (14) While many States have agreedto limit their production and possession of some types of WMD and conventional weapons, they mayhave conditioned their consent on the conduct of other States, and may be able to revoke theirconsent in accordance with any such conditional agreement. While secret development of WMDon the part of a State that has agreed not to engage in such conduct would constitute a breach of atreaty obligation, it is not necessarily a crime or an act of aggression under international law merelyto possess such weapons. The center of the nuclear nonproliferation regime is the Nuclear Nonproliferation Treaty ("NPT"). (15) The treaty defines nuclear weaponsStates as those States that had manufactured anddetonated a nuclear weapon prior to January 1, 1967. (16) The treaty thus allows five nuclear powers- the United States, Great Britain, Russia, France and China - to manufacture and possess nuclearweapons, but prohibits the transfer of such weapons to other States. (17) All other States Parties to theNPT have agreed not to acquire nuclear weapons in return for assistance in developing peaceful usesfor nuclear power. (18) The five declared nuclearpowers are committed under the treaty to "pursuenegotiations in good faith on effective measures relating to cessation of the nuclear arms race at anearly date and to nuclear disarmament, and on a treaty on general and complete disarmament understrict and effective international control." (19) StatesParties may withdraw from the NPT on threemonths' notice if "extraordinary events, related to the subject matter of [the NPT], have jeopardizedthe supreme interests of its country." (20) The chief means of verification is through inspections carried out by the International Atomic Energy Agency ("IAEA"). Non-nuclear-weapon States Parties may stockpile weapons-grade nuclearmaterial, provided that the nuclear material is subject to IAEA safeguards. Each non-nuclear StateParty is required to negotiate a set of safeguards for verification and accounting of nuclear materialsat its declared nuclear sites. No State Party is permitted to transfer nuclear materials or equipmentfor processing them to any non-nuclear State for peaceful purposes unless the transferred goods aresubject to IAEA safeguards. (21) The IAEA isempowered to conduct "special inspections" if a StateParty reports a loss of inspected material, but is not empowered to take any action if it suspects thatclandestine nuclear programs are taking place at undisclosed sites. In the event it discovers aviolation, the IAEA is to report the noncompliance to the U.N. Security Council and GeneralAssembly, as with other arms control agreements. Neither the NPT nor IAEA regulations providesfor any penalty in case of breach. (22) The restriction on the transfer of nuclear weapons and related technology is implemented at the national level through export control laws. (23) Some nations have joined together to form multilateralexport control groups in order to coordinate nonproliferation efforts. (24) These groups harmonize listsof sensitive materials and technologies that must be controlled in order to prevent proliferation ofnuclear weapons and methods by which member countries are to prevent their transfer. Regimemembers agree to restrict such trade by implementing laws, regulations, and licensing requirementsapplicable to citizens and residents. They may also agree to share information about exports andlicenses. The regimes are voluntary and non-binding. (25) International efforts to prohibit the use of chemical weapons began more than a century ago as part of the effort to regulate warfare.