Whether the United States should initiate construction of a limited national missile defense system became a significant issue for the Clinton administration in the summer of 2000. Central to the national defense system discussion was a concern that such a move would violate the Anti-Ballistic Missile Treaty ("ABM Treaty") signed with the Soviet Union in 1972.(1) The administration considered a number of different approaches to build a national missile defense system, including the possibility that the ABM Treaty could be interpreted to allow preliminary stages of construction to begin without technically violating the treaty. After considerable deliberation, the Clinton administration decided not to insist upon such a broad interpretation of the ABM Treaty. However, the discussion surrounding that possibility highlighted an important problem in international law: what happens when one party to an international treaty unilaterally changes a long-standing and previously universally accepted interpretation of the treaty?
The United States and the Soviet Union signed the ABM Treaty in the midst of the Cold War as an effort to slow the arms race by reducing the number of weapons and limiting the defense systems available to both sides. Article I of the treaty takes a strong stance against nation-wide defense systems, stating "[e]ach party undertakes not to deploy ABM systems for a defense of the territory of its country and not to provide a base for such a defense."2 The treaty limits even the testing of several kinds of defense systems in Article V: "Each party undertakes not to develop, test, or deploy AMB systems or components which are sea-based, air-based, space-based, or mobile land-based."3 The treaty leaves in place the ability to deploy very limited defense systems that are unable to protect the parties' major cities. The idea driving the limitations on defense systems was that if neither side could survive a first strike with
a retaliatory capability intact, then neither side would have an incentive to order that first strike.4 Any defense system capable of defending either side's major cities was considered to be a negative contribution to the arms race, because once one side had such a defense capability the other side would work until it produced the technology necessary to pierce the system.
At the time that the ABM Treaty was signed, the United States and the Soviet Union were among the only countries with the capability of launching intercontinental nuclear ballistic missiles.5 The global climate concerning nuclear weapons has changed considerably since the treaty was ratified. In recent years, smaller nations such as North Korea and Iran have developed nuclear technology. The possibility that the United States may be vulnerable to a nuclear attack from such "rogue states" fueled a desire among both Congress and the Clinton administration to deploy a limited defense system despite the ABM Treaty.
In early June 2000, President Clinton met with Russian President Vladimir Putin to discuss the US plan to build a limited defense system in response to the threat from "rogue states." The plan included the construction of 100 interceptor missiles in Alaska to protect the United States from incoming missiles. Russia made it clear during the summit that the proposed missile defense system would constitute a violation of the ABM treaty. Clinton rejected Putin's suggestion that the two nations create a joint Russo-US theater defense system of a much smaller scale than the national system that Clinton proposed.6
Following the summit, the Clinton administration suggested that the ABM Treaty could be interpreted to allow for the initial phases of construction of a limited defense system without violating the terms of the treaty. Article II of the ABM Treaty states that "The ABM System components ... include those which are ... under construction."7 The administration argued that the phrase "under construction" could be interpreted so that the United States could pour the cement on the project without the system actually being "under construction. …