# Anti-Ballistic Missile Treaty

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The Anti-Ballistic Missile Treaty (ABM Treaty or ABMT) was a treaty between the United States and the Soviet Union on the limitation of the anti-ballistic missile (ABM) systems used in defending areas against ballistic missile-delivered nuclear weapons. Under the terms of the treaty, each party was limited to two ABM complexes, each of which was to be limited to 100 anti-ballistic missiles.[1]

Signed in 1972, it was in force for the next 30 years.[2] Following the dissolution of the Soviet Union, in 1997 the United States and four former Soviet republics agreed to succeed to the treaty. In June 2002 the United States withdrew from the treaty, leading to its termination.

## Background

Throughout the late 1950s and into the 1960s, the United States and the Soviet Union had been developing missile systems with the ability to shoot down incoming ICBM warheads. During this period, the US considered the defense of the US as part of reducing the overall damage inflicted in a full nuclear exchange. As part of this defense, Canada and the US established the North American Air Defense Command (now called North American Aerospace Defense Command).

By the early 1950s, US research on the Nike Zeus missile system had developed to the point where small improvements would allow it to be used as the basis of an operational ABM system. Work started on a short-range, high-speed counterpart known as Sprint to provide defense for the ABM sites themselves. By the mid-1960s, both systems showed enough promise to start development of base selection for a limited ABM system dubbed Sentinel. In 1967, the US announced that Sentinel itself would be scaled down to the smaller and less expensive Safeguard. Soviet doctrine called for development of its own ABM system and return to strategic parity with the US. This was achieved with the operational deployment of the A-35 ABM system and its successors, which remain operational to this day.

The development of multiple independently targetable reentry vehicle (MIRV) systems allowed a single ICBM to deliver as many as ten separate warheads at a time. An ABM defense system could be overwhelmed with the sheer number of warheads.[3] Upgrading it to counter the additional warheads would be economically unfeasible: The defenders required one rocket per incoming warhead, whereas the attackers could place 10 warheads on a single missile at a reasonable cost. To further protect against ABM systems, the Soviet MIRV missiles were equipped with decoys; R-36M heavy missiles carried as many as 40.[4] These decoys would appear as warheads to an ABM, effectively requiring engagement of five times as many targets and rendering defense even less effective.

## ABM Treaty

The United States first proposed an anti-ballistic missile treaty at the 1967 Glassboro Summit Conference during discussions between U.S. Secretary of Defense Robert McNamara and Chairman of the Council of Ministers of the Soviet Union Alexei Kosygin. McNamara argued both that ballistic missile defense could provoke an arms race, and that it might provoke a first-strike against the nation fielding the defense. Kosygin rejected this reasoning.[5] Following the proposal of the Sentinel and Safeguard decisions on American ABM systems, the Strategic Arms Limitation Talks began in November 1969 (SALT I). By 1972 an agreement had been reached to limit strategic defensive systems. Each country was allowed two sites at which it could base a defensive system, one for the capital and one for ICBM silos.

The treaty was signed during the 1972 Moscow Summit on May 26 by the President of the United States, Richard Nixon and the General Secretary of the Communist Party of the Soviet Union, Leonid Brezhnev; and ratified by the US Senate on August 3, 1972.

The 1974 Protocol reduced the number of sites to one per party, largely because neither country had developed a second site.[6] The sites were Moscow for the USSR and the North Dakota Safeguard Complex for the US, which was already under construction.

### Missiles limited by the treaty

The Treaty limited only ABMs capable of defending against "strategic ballistic missiles", without attempting to define "strategic". It was understood that both ICBMs and SLBMs are obviously "strategic".[7] Both countries did not intend to stop the development of counter-tactical ABMs. The topic became disputable as soon as most potent counter-tactical ABMs started to be capable of shooting down SLBMs (SLBMs naturally tend to be much slower than ICBMs), nevertheless both sides continued counter-tactical ABM development.[7]

## After the SDI announcement

On March 23, 1983 Ronald Reagan announced the Strategic Defense Initiative, a research program into ballistic missile defense which would be, "consistent with our obligations under the ABM Treaty". The project was a blow to Yuri Andropov's so-called "peace offensive". Andropov said that "It is time they [Washington] stopped... search[ing] for the best ways of unleashing nuclear war... Engaging in this is not just irresponsible. It is insane".[8]

Regardless of the opposition, Reagan gave every indication that SDI would not be used as a bargaining chip and that the United States would do all in its power to build the system. The Soviets were threatened because the Americans might have been able to make a nuclear first strike possible. In The Nuclear Predicament, Beckman claims that one of the central goals of Soviet diplomacy was to terminate SDI. A surprise attack from the Americans would destroy much of the Soviet ICBM fleet, allowing SDI to defeat a “ragged” Soviet retaliatory response. Furthermore, if the Soviets chose to enter this new arms race, they would further cripple their economy. The Soviets could not afford to ignore Reagan’s new endeavor, therefore their policy at the time was to enter negotiations with the Americans.[9][10] By 1987, however, the USSR withdrew its opposition, concluding the SDI posed no threat and scientifically "would never work."[11][12]

SDI research went ahead, although it did not achieve the hoped-for result. SDI research was cut back following the end of Reagan's presidency, and in 1995 it was reiterated in a presidential joint statement that "missile defense systems may be deployed... [that] will not pose a realistic threat to the strategic nuclear force of the other side and will not be tested to... [create] that capability." This was reaffirmed in 1997.

## US withdrawal

Although the Soviet Union ceased to exist in December 1991, in the view of the U.S. Department of State, the treaty continued in force.[13] An additional memorandum of understanding was prepared in 1997, establishing Belarus, Kazakhstan, the Russian Federation, and Ukraine as successor states to the Soviet Union, for the purposes of the treaty.

On December 13, 2001, George W. Bush gave Russia notice of the United States' withdrawal from the treaty, in accordance with the clause that required six months' notice before terminating the pact—the first time in recent history that the United States has withdrawn from a major international arms treaty.[14] This led to the eventual creation of the American Missile Defense Agency.[15]

Supporters of the withdrawal argued that it was a necessity in order to test and build a limited National Missile Defense to protect the United States from nuclear blackmail by a rogue state. The withdrawal had many critics as well as supporters. John Rhinelander, a negotiator of the ABM treaty, predicted that the withdrawal would be a "fatal blow" to the Nuclear Non-Proliferation Treaty and would lead to a "world without effective legal constraints on nuclear proliferation." The construction of a missile defense system was also feared to enable the US to attack with a nuclear first strike.

Russia and the United States signed the Strategic Offensive Reductions Treaty in Moscow on May 24, 2002. This treaty mandates cuts in deployed strategic nuclear warheads, but without actually mandating cuts to total stockpiled warheads, and without any mechanism for enforcement.

## References

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Anti-Ballistic Missile Treaty [1] 1974 Protocol [2]