Although of unlimited duration, the treaty was subject to review every five years, with a 6-month withdrawal notification time.

The Interim Agreement

Under the Interim Agreement the parties concurred in limiting the numbers of strategic missile launchers on both land and sea to the numbers and types then existing or under construction, but they allowed for the improvement of those existing types. The agreement was to remain in force for five years, with a 6-month notification of termination, but both sides informally agreed to extend it beyond expiration.

Salt II

The second round of negotiations, called SALT II, resulted in the Vladivostok Accord of November 1974 and the SALT II Treaty, signed on June 18, 1979. The former placed limits, for the first time, on the total numbers of strategic launchers and of US strategic bombers.

The SALT II Treaty set precise limits on the numbers of each type and subtype of strategic launcher and specifically defined each type. It provided for destruction of all launchers beyond the number allowed, but permitted the testing and development of certain kinds of launchers. Verification was provided once again by national technical means, with no on-site inspection. The SALT II Treaty met with stiff resistance when it was presented to the US Senate for ratification, and in January 1980 the Senate debate was postponed at the request of President Jimmy Carter in retaliation for Soviet intervention in Afghanistan.

Although the treaty never entered into force, both the United States and the Soviet Union pledged to abide by its limits. In May 1982 President Ronald Reagan, an opponent of SALT II, advanced his own proposal for a Strategic Arms Reduction Treaty (START), calling for deep cuts in land-based missiles (in which the USSR was perceived to hold an advantage). This became the US negotiating position at Geneva, but the Soviets broke off the talks in late 1983 to protest the deployment of US intermediate-range missiles in Europe. When formal negotiations resumed in January 1985, the United States continued to focus on land-based weapons, while the USSR demanded that space weaponry-as envisioned in the United States Strategic Defense Initiative-be the leading item on the agenda. The Soviets eventually dropped this demand, and direct talks between President Reagan and Soviet leader Mikhail Gorbachev led to the signing of the Intermediate Range Nuclear Forces Treaty in December 1987. Negotiations continued after George Bush was elected US president in 1988, and in July 1991 he and Gorbachev signed the START I Treaty, by which it was agreed to reduce the number of nuclear warheads by about 25 per cent. This treaty was not fully implemented until 1993, when the Ukrainian parliament ratified it.