SALT I, the first series of Strategic Arms Limitation Talks, extended from November 1969 to May 1972. During that period the United States and the Soviet Union negotiated the first agreements to place limits and restraints on some of their central and most important armaments. In a Treaty on the Limitation of Anti-Ballistic Missile Systems, they moved to end an emerging competition in defensive systems that threatened to spur offensive competition to still greater heights. In an Interim Agreement on Certain Measures With Respect to the Limitation of Strategic Offensive Arms, the two nations took the first steps to check the rivalry in their most powerful land- and submarine-based offensive nuclear weapons.

The earliest efforts to halt the growth in strategic arms met with no success. Strategic weapons had been included in the U.S. and Soviet proposals for general and complete disarmament. But the failure of these comprehensive schemes left strategic arms unrestrained. The United States was the first to suggest dissociating them from comprehensive disarmament plans -- proposing, at the Geneva-based Eighteen-Nation Disarmament Committee in January 1964, that the two sides should "explore a verified freeze of the number and characteristics of their strategic nuclear offensive and defensive vehicles."

The competition in offensive and defensive armaments continued. By 1966 the Soviet Union had begun to deploy an antiballistic missile defense around Moscow; and that year the Peoples Republic of China successfully tested a nuclear missile. In the United States, research and development were leading to U.S. deployment of its own ABM system.

In March 1967, after an exchange of communication with Soviet leaders, President Johnson announced that Premier Kosygin had indicated a willingness to begin discussions. Attempts to get talks underway, however, were not successful.

On September 18, 1967, the United States announced that it would begin deployment of a "thin" antiballistic missile (ABM) system. The Administration emphasized that the deployment was intended to meet a possible limited Chinese ICBM threat, to underscore U.S. security assurances to its allies by reinforcing the U.S. deterrent capability, and to add protection against "the improbable but possible accidental launch of an intercontinental missile by one of the nuclear powers." This program for limited ABM defense brought sharply divided views in public and congressional debate regarding the efficacy and desirability of an ABM system and its possible effects on the arms race.

In announcing the U.S. decision, Secretary of Defense McNamara said,

Let me emphasize -- and I cannot do so too strongly -- that our decision to go ahead with a limited ABM deployment in no way indicates that we feel an agreement with the Soviet Union on the limitation of strategic nuclear offensive and defensive forces is in any way less urgent or desirable.

Through diplomatic channels in Washington and Moscow, discussions with Soviet representatives in the ENDC, and exchanges at the highest levels of the two governments, the United States continued to press for a Soviet commitment to discuss strategic arms limitation. But it was not until the following year that evidence of a Soviet reassessment of its position emerged. On July 1, 1968, President Johnson announced, at the signing of the Non-Proliferation Treaty, that agreement had been reached with the Soviet Union to begin discussions on limiting and reducing both strategic nuclear weapons delivery systems and defense against ballistic missiles. The date and place for the talks had not yet been announced, when, on August 20, the Soviet Union began its invasion of Czechoslovakia, an event that postponed the talks indefinitely.

On January 20, 1969, the day that President Nixon assumed office, a statement by the Soviet Foreign Ministry expressed willingness to discuss strategic arms limitations. The new President promptly voiced his support for talks, and initiated, under the aegis of the National Security Council, an extensive and detailed review of the strategic, political, and verification aspects of the problem.

In October, the White House and the Kremlin announced that the Strategic Arms Limitation Talks would begin in Helsinki on November 17, 1969, "for preliminary discussion of the questions involved." The Director of ACDA, Gerard Smith, was named to head the U.S. delegation and led it throughout the two and a half-year series of SALT I negotiations.

In the first session of the talks, from November 17 to December 22, each side gained a better understanding of the others views and of the range of questions to be considered. It was agreed that the talks would be private, to encourage a free and frank exchange, and the stage was set for the main negotiations, which opened in Vienna in April 1970. Sessions thereafter alternated between Helsinki and Vienna until the first accords were reached in May 1972. (When SALT II began, in November 1972, to reduce the administrative burdens involved in shifting sites it was agreed to hold them henceforth in one place -- Geneva.)

Soviet and American weapons systems were far from symmetrical. The Soviet Union had continued its development and deployment of heavy ballistic missiles and had overtaken the U.S. lead in land-based ICBMs. During the SALT I years alone Soviet ICBMs rose from around 1,000 to around 1,500, and they were being deployed at the rate of some 200 annually. Soviet submarine-based launchers had quadrupled. The huge payload capacity of some Soviet missiles ("throw-weight") was seen as a possible threat to U.S. land-based strategic missiles even in heavily protected ("hardened") launch-sites.

The United States had not increased its deployment of strategic missiles since 1967 (when its ICBMs numbered 1,054 and its SLBMs 656), but it was conducting a vigorous program of equipping missiles with "Multiple Independently-targeted Re-entry Vehicles" (MIRV). "MIRVs" permit an individual missile to carry a number of warheads directed at separate targets. MIRVs thus gave the United States a lead in numbers of warheads. The United States also retained a lead in long-range bombers. The Soviet Union had a limited ABM system around Moscow; the United States had shifted from its earlier plan for a "thin" ABM defense of certain American cities and instead began to deploy ABMs at two land-based ICBM missile sites to protect its retaliatory forces. (The full program envisaged 12 ABM complexes.)

Besides these asymmetries in their strategic forces, the defense needs and commitments of the two parties differed materially. The United States had obligations for the defense of allies overseas, such as Western Europe and Japan, while the Soviet Unions allies were its near neighbors. All these circumstances made for difficulties in equating specific weapons, or categories of weapons, and in defining overall strategic equivalence.

Two initial disagreements presented obstacles. The Soviet representatives sought to define as "strategic" -- i.e., negotiable in SALT-- any U.S. or Soviet weapons system capable of reaching the territory of the other side. This would have included U.S. "forward-based systems," chiefly short-range or medium-range bombers on aircraft carriers or based in Europe, but it would have excluded, for example, Soviet intermediate-range missiles aimed at Western Europe. The United States held that weapons to be negotiated in SALT comprised intercontinental systems. Its forward-based forces served to counter Soviet medium-range missiles and aircraft aimed at U.S. allies. To accept the Soviet approach would have prejudiced alliance commitments.

After initial attempts to reach a comprehensive agreement failed, the Soviets sought to restrict negotiations to antiballistic missile systems, maintaining that limitations on offensive systems should be deferred. The U.S. position was that to limit ABM systems but allow the unrestricted growth of offensive weapons would be incompatible with the basic objectives of SALT and that it was essential to make at least a beginning at limiting offensive systems as well. A long deadlock on the question was finally broken by exchanges at the highest levels of both governments. On May 20, 1971, Washington and Moscow announced that an understanding had been reached to concentrate on a permanent Treaty to limit ABM systems, but at the same time to work out certain limitations on offensive systems, and to continue negotiations for a more comprehensive and long-term agreement on the latter.

In a summit meeting in Moscow, after two and a half years of negotiation, the first round of SALT was brought to a conclusion on May 26, 1972, when President Nixon and General Secretary Brezhnev signed the ABM Treaty and the Interim Agreement on strategic offensive arms.

Intensive research had gone into finding ways of verifying possible agreements without requiring access to the territory of the other side. Both the ABM Treaty and the Interim Agreement stipulate that compliance is to be assured by "national technical means of verification." Moreover, the agreements include provisions that are important steps to strengthen assurance against violations: both sides undertake not to interfere with national technical means of verification. In addition, both countries agree not to use deliberate concealment measures to impede verification.

The basic provisions of each SALT I agreement are briefly reviewed in sections that follow. The two accords differ in their duration and inclusiveness. The ABM Treaty "shall be of unlimited duration," but each Party has the right to withdraw on six months notice if it decides that its supreme interests are jeopardized by "extraordinary events related to the subject matter of this Treaty." The Interim Agreement was for a five-year span, and covered only certain major aspects of strategic weaponry. The agreements are linked not only in their strategic effects, but in their relationship to future negotiations for limitations on strategic offensive arms. A formal statement by the United States stressed the critical importance it attached to achieving more complete limitations on strategic offensive arms.

The two agreements were accompanied by a number of "Agreed Statements" that were agreed upon and initialed by the Heads of the Delegations. When the two agreements were submitted to the U.S. Congress, they were also accompanied by common understandings reached and unilateral statements made during the negotiations. These were intended to clarify specific provisions of the agreements or parts of the negotiating record. The three groups of items are reproduced here with the texts of the agreements.