How the ABM Treaty Obstructs Missile Defense

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How the ABM Treaty Obstructs Missile Defense

July 10, 2001 8 min read
Baker Spring
F.M. Kirby Research Fellow in National Security Policy

The United States, as a matter of policy, continues to observe the restrictions of the 1972 Anti-Ballistic Missile (ABM) Treaty with the former Soviet Union. It does so in spite of the fact that there have been no other parties to the treaty since the Soviet Union ceased to exist nearly 10 years ago--a situation that should have rendered the treaty null and void. The United States' continued observance of the treaty's restrictions poses an insurmountable obstacle to the development and deployment of an effective defense against ballistic missiles to protect the American people, America's armed forces, and its allies.

The following restrictions of the ABM Treaty effectively bar the United States from fielding an effective missile defense system or even exploring the full array of options available:

  • Article I of the treaty prohibits the deployment of a system capable of defending all U.S. territory against missile attack, and even building the base for such a territorial defense.

  • Article III of the treaty, as amended by a 1974 protocol, prohibits the deployment of more than 100 fixed, land-based interceptors and, even at that limit, allows only those at a single specific site, which the United States designated as Grand Forks, North Dakota.

  • Article V of the treaty prohibits not only the deployment, but even the development and testing of sea-based, air-based, space-based, or mobile land-based systems.

  • Article VI of the treaty prohibits giving non-ABM systems an ABM capability or testing them in an ABM mode.

  • Article IX of the treaty prohibits the transfer of ABM systems or components to other countries.

President Bush, in his May 1 speech at the National Defense University in Washington, made it clear that he wants to field an effective defense as soon as possible and recognizes that the United States must move beyond the ABM Treaty to do so. It can be expected that, in the near future, President Bush will order the Department of Defense to cease the continued unilateral enforcement of the ABM Treaty's restrictions.

In this event, his Administration needs to explain to the American people and interested foreign states what it wants to do to ensure the protection of the United States and its allies and how those activities are prohibited by the continued observance of ABM Treaty restrictions. In short, the Bush Administration needs to provide concrete examples that show that the ABM Treaty no longer serves U.S. interests.


At the outset, the Bush Administration needs to make it clear how specific terms of the treaty prohibit even the exploration of options for America's defense. Critics of proposals for a missile defense strategy demand that any missile defense system be fully tested before ABM Treaty restrictions are abandoned. Yet restrictions in the treaty ban a wide variety of testing and development activities.

The Administration should make this point by providing to the public a list of proposed development and testing activities that are blocked by
continued enforcement of the treaty. The Administration could highlight the following short list of relatively near-term development and testing

  • Testing a sea-based interceptor against a target ballistic missile that flies faster than five kilometers per second or farther than 3,500 kilometers. Many defenders of the ABM Treaty argue that this kind of test, which would demonstrate the ability of sea-based interceptors to defend the territory of the United States, is inconsistent with either Article V or Article VI of the treaty, or both.

  • Testing a mobile land-based interceptor, such as THAAD, against a target ballistic missile that flies faster than five kilometers per second or farther than 3,500 kilometers. ABM Treaty defenders object to this kind of test on the same grounds that they opposed testing of the sea-based interceptor--violations of Article V and/or Article VI of the treaty.

  • Testing the air-borne laser against a target ballistic missile in the boost phase. ABM Treaty supporters may be divided as to whether or not this test is inconsistent with the treaty. Some of them, however, will assert that countering ballistic missiles in the boost phase, when all such missiles are traveling relatively slowly, makes it impossible to distinguish between the air-launched boost-phase defenses (which are permissible for countering short-range defense systems) and defenses for countering long-range missiles (which are prohibited).

    The defenders of the treaty will point to a provision in a 1978 agreed statement adopted by the Standing Consultative Commission. This provision states that systems that may otherwise be considered to be non-ABM systems shall be deemed to have been tested in an ABM mode if they are tested against target ballistic missiles that have flight trajectories that are consistent with strategic ballistic missiles "over the portions of the flight trajectory involved in such testing."

  • Testing a space-based interceptor against any target ballistic missile. This is where ABM Treaty supporters take their most extreme position. They would prohibit this test even if it was conducted against a target ballistic missile that was undeniably a theater-range missile.

    All agree that the ABM Treaty was not designed to inhibit defenses against shorter-range missiles in any way. In regard to sea-based and mobile land-based interceptors, treaty defenders do not object to tests against shorter-range missiles. However, they would apply a blanket prohibition of space-based interceptors, claiming that all such interceptors have a direct ABM capability regardless of the kind of target ballistic missile they are tested against. They argue that space-based interceptor tests are inconsistent with Articles V and VI of the treaty under all circumstances.


Testing and development activities should not be the Administration's sole concern regarding the continued enforcement of ABM Treaty restrictions. Even some construction and deployment activities of an expedited missile defense program could run up against the treaty's restrictions. A short list of prohibited activities in this area might include the following.

  • Construction of an ABM battle management radar on Shemya. In 2000, the Clinton Administration contemplated initiating construction of an ABM battle management radar on Shemya Island in the Aleutians in the spring of 2001. Ultimately, President Clinton chose to defer construction but acknowledged that, at some point, this construction activity would exceed ABM Treaty restrictions.

    If the Bush Administration opts to pursue this plan, it will run into the same problem. The construction of the radar equipment would violate Article III of the treaty, which, as amended, limits the deployment of such a radar to a designated area near an ICBM field or the nation's capital.

  • Construction of a sea-based ABM radar. There is also the possibility of deploying an ABM battle management radar on a ship. This would make the radar mobile and thus potentially more survivable in the event of an attack. It would also be easier to construct the radar because the construction could take place without the limitations of Shemya Island's hard climate and short construction season. Defenders of the ABM Treaty, however, would argue that the construction of a sea-based ABM radar is not only inconsistent with Article III of the treaty, but that it also violates Article V's prohibition on the deployment of sea-based ABM components.

  • Upgrading existing early warning radar. The Clinton Administration's missile defense plan also included a provision to upgrade existing early warning radar deployed both in the United States and abroad. In the view of ABM Treaty supporters, giving early warning radar an ABM capability is inconsistent with Article VI of the treaty. This article specifically prohibits giving non-ABM systems (including early warning radar) ABM capabilities. Further, Article IX of the treaty prohibits the transfer of ABM components to allies. Thus, upgrading the early warning radar located abroad is prohibited under the continued enforcement of the ABM Treaty.

  • Deploying land-based interceptors outside Grand Forks. The Bush Administration could also undertake an expedited deployment of fixed, land-based interceptors. The ABM Treaty allowed the deployment of up to 100 such interceptors at Grand Forks, North Dakota, as the site the U.S. designated as an ABM deployment area under Article III of the treaty.

    The Clinton Administration's plan included the deployment of the interceptors in Alaska, while acknowledging that this would be inconsistent with Article III. If the Bush Administration wants to deploy such interceptors in Alaska (or in any area other than Grand Forks or Washington, D.C.) it must seek relief from ABM Treaty enforcement. Likewise, it would have to leave the treaty in order to deploy more than 100 interceptors even at the allowed sites, or to deploy any interceptors that are capable of defending all U.S. territory or deemed to constitute the base for such a "territorial defense" under Article I.

  • Fielding the Navy's "extended air defense" system. The Navy has briefed the Bush Administration on an emergency deployment option for countering North Korean missiles located at known launch sites. The plan calls for modifying two existing AEGIS class ships and homeporting them in Japan. The modified ships would use the existing Standard Missile-2 Block IV to counter North Korean missiles in the boost phase.

    The Navy has dubbed this emergency deployment option "extended air defense." Deployment would take 12 to 18 months and would cost between $150 million and $200 million. ABM Treaty defenders argue that fielding this system, if it is used to counter long-range North Korean missiles, is inconsistent with Articles V and VI of the treaty. Article V bars the deployment of sea-based ABM systems, while Article VI prohibits giving non-ABM systems, such as an air defense system, an ABM capability.


The final area of constraint imposed by the continued enforcement of the ABM Treaty is neither precisely a development nor a deployment activity. It is best described as a cooperative alliance activity.

If the Bush Administration wants to transfer ABM components to Japan to expand the existing cooperative program for developing the Navy Theater-Wide system, or to Israel to enhance the capability of the Arrow system, it will have to obtain relief from ABM Treaty enforcement. Article IX of the ABM Treaty prohibits the United States from transferring to its allies ABM Treaty components. Agreed Statement G, accompanying the treaty, further prohibits even the transfer of technical descriptions and blueprints of ABM systems and components.


The numerous restrictions of the ABM Treaty, when taken together, comprise a blanket prohibition against fielding an effective missile defense system. However, the Bush Administration cannot afford to simply assert this truth and think it is self-evident. Rather, the President should explain in detail exactly what he wants to do to ensure the protection of the United States and its allies, and he should show how continued enforcement of the ABM Treaty stands in the way of this action.

Baker Spring is F. M. Kirby Research Fellow in National Security Policy in the Kathryn and Shelby Cullom Davis Institute for International Studies at The Heritage Foundation. These remarks were presented at a conference on "Defending the Northeast, the Nation, and America's Allies from Ballistic Missile Attack" organized by the Institute for Foreign Policy Analysis and held in Valley Forge, Pennsylvania, on June 28, 2001.


Baker Spring

F.M. Kirby Research Fellow in National Security Policy