North Korea’s withdrawal from the Nuclear Nonproliferation Regime and announcement of a nuclear weapons program was an unfortunate development, which the international community must work to reverse. Some US officials are, however, advocating for a policy of interdicting  North Korean ships – a policy that would do more harm than good to international stability by undermining the International Law of the Sea.
The International Law of the Sea is one of the most comprehensive and well-established bodies of international regulatory norms in existence. The Law of the Sea regime (LOS) is buttressed by longstanding international norms, and formal legal agreements, critical to creating a more secure international environment. 
The Law of the Sea grants several freedoms, including the right to navigation on the high seas and rights to transit  through international straits, exclusive economic zones (EEZ), and the territorial and archipelagic waters of another state. The regime does bar a select number of illegal activities, including piracy, slave trade, illicit traffic in narcotic drugs or psychotropic substances, and unauthorized broadcasting, and grants states the right to intervene in such activities. 
There is nothing in the LOS regime that explicitly prohibits transit of weapons of mass destruction or gives States rights to interdict such transit. On the contrary, a number of States, including the United States, have actively opposed the development of such prohibitive norms or interpretations of international law that would inhibit the transit of weapons of mass destruction by the seas or air, and cite the rights and privileges established in the Law of the Sea to affirm their unhindered military use of the oceans. Nuclear weapon states such as the US, UK and France have continuously worked to ensure that their ability to transit nuclear weapons is not hindered by regional nuclear weapons free zones or UN efforts to create a Nuclear Weapon Free Southern Hemisphere. The US, UK and France, along with Japan, have also asserted their rights to transit nuclear materials – in particular reprocessed plutonium – through the high seas and through the EEZ’s of coastal States. In addition, a number of States, including the United States, France, Israel, China, Russia and Italy, export missile technology transiting through the oceans to do so.
In contrast to this general assertion of rights to transit nuclear weapons, missile technology , fissile materials and other materials related to weapons of mass destruction, the US is currently advocating for the selected interdiction of such materials to and from certain states of concern to the Bush Administration as a means to stem proliferation. Ten countries have now joined what is known as the Proliferation Security Initiative (PSI), which met in Madrid, Spain in early June and in Brisbane, Australia in the beginning of July 2003 . Members of PSI include: Australia, France, Germany, Italy, Japan, the Netherlands, Poland, Portugal, Spain, and the United Kingdom.
However, there are limitations to the transit that countries can legally inhibit in their territorial waters and EEZs and even stricter limitations on what can be intercepted on the High Seas.
The legal implications of arms interdictions on the oceans depend greatly on the nature of interdictions and the way the interdictions are undertaken. Some States have agreed to export controls amongst themselves, such as those laid out in the Missile Technology Control Regime. However, the States of concern to the US, such as North Korea, China, Pakistan and Iran, are not members and so are not bound by these controls. It might be legal to interdict shipments on the High Seas that have been deemed by the Security Council or the Law of the Sea Tribunal to violate the Law of the Sea and to constitute a threat to the peace. This option is pursued in a recent strategy issued by the Council of the European Union calling on the EU to support a Security Council Resolution that would arms interdictions “when appropriate.”  Also, in territorial waters it might be possible for the coastal State to determine the transit of missiles or WMD to be a threat to its security and thus prohibit such transit deeming it to be non-innocent passage.
Any interdictions outside those explicitly allowed in the existing International Law of the Sea regime would clearly violate the freedom of navigation on the high seas and the right of innocent passage through territorial waters.
Australian Foreign Minister Alexander Downer has recognized that there is a “very real difficulty in terms of vessels that might be going through the high seas because international law requires that those ships should not be intercepted,”  and that there might therefore “need to be some change to international law to facilitate these types of interdictions, to stop illicit trade.” However, changing the Law of the Sea would be a long process requiring extensive negotiations and would unlikely yield the discriminatory approach desired by the PSI of allowing transit by certain States but not others.
The likelihood that the US and PSI will thus develop an interdiction strategy outside international law is reinforced by the current trend in US policy towards dismantling norms that prevent the US from exercising its military dominance. The US has moved away from multi-lateral non-proliferation solutions, withdrawn from the Anti-Ballistic Missile treaty, abandoned START II, failed to ratify the Comprehensive Test Ban Treaty, and stalled efforts to improve the Biological Weapons Convention regime. The controversy over the UK and US use of intelligence in Iraq will also bring into question the legitimacy of intelligence information used to justify interdictions regarding the existence of arms and material shipments and their intended destination and/or use.
Restricting the transit of weapons of mass destruction would be a positive development in furthering arms control and stemming proliferation, if such norms were carefully developed by the international community and applied uniformly. International law cannot, however, maintain its integrity if applied whimsically or discriminately, or if defined by a small “coalition of the willing.” While PSI membership may appear to be an easy way for leaders of certain countries to get back into the good graces of the Bush administration after disagreements over Iraq, if they contribute to the degradation of LOS it will likely come back to haunt them. If leaders of the states participating in the PSI attempt to exchange LOS norms for selective nonproliferation measures, they should realize that such a trade-off could eventually restrict their own country’s access to international waters. If members of the international community begin to allow the erosion of the Law of the Sea to suite the policy goals of the sole existing superpower, they should not expect that such concessions would be easily reversed.
* This article is a summary of a longer piece pending publication in Science for Democratic Action, the newsletter of the Institute for Energy and Environmental Research.
**Devon Chaffee is the Research and Advocacy Coordinator of the Nuclear Age Peace Foundation
1. Interdicting: intercepting ships and ensuring that no proscribed activities are being conducted.
2. Such formal agreements include the four 1958 Conventions that resulted from the Geneva Conference on the law of the sea, to which the US is a party, and the 1982 UN Convention on the Law of the Sea (UNCLOS), which President Ronald Reagan decided not to sign onto for fear that it could interfere with certain US sovereign prerogatives. The US has however signed the 1994 Agreement relating to the Implementation of Part XI of the U.N. Convention on the Law of the Sea.
3. Transit through territorial waters is limited to innocent passage. According to the 1958 Convention on the Territorial Sea “Passage is innocent so long as it is not prejudicial to the peace, good order or security of the coastal state.”
4. In addition to their codification into the law of the sea through the 1958 and the 1982 Conventions, the prohibition of these activities has been codified by a series of multilateral treaties including: 1965 Agreement for the Prevention of Broadcasts Transmitted from Stations outside National Territories; General Act for the Repression of the Slave Trade, 1890;
5. See UN Register of Conventional Arms, http://disarmament.un.org/UN_REGISTER.nsf and Nuclear and Missile Trade and Developments, The Nonproliferation Review, Center for Nonproliferation Studies,http://cns.miis.edu/pubs/npr/vol05/53/db53.pdf
6. Chairman’s Statement, Proliferation Security Initiative, Brisbane Meeting, July 9-10, 2003.http://www.dfat.gov.au/globalissues/psi/
7. Strategy against Proliferation of Weapons of Mass Destruction and its corresponding Action Plan adopted by the Council of the European Union on April 14, 2003.
8. “N Korea Ships Face more Scrutiny,” BBC, June 11, 2003.
9. Sonni Efron and Barbara Demick, “11 nations to Discuss Blocking Shipments of Weapons Materials,” Los Angeles Times. June 12, 2003.