Begun in November 1969, by May 1972, the Strategic Arms Limitation Talks (SALT) had produced both the Anti-Ballistic Missile (ABM) Treaty, which limited strategic missile defenses to 200 (later 100) interceptors each, and the Interim Agreement Between the United States of America and the Union of Soviet Socialist Republics on Certain Measures with Respect to the Limitation of Strategic Offensive Arms (Interim Agreement or SALT I), an executive agreement that capped U.S. and Soviet intercontinental ballistic missiles (ICBM) and submarine-launched ballistic missile (SLBM) forces. Under the Interim Agreement, both sides pledged not to construct new ICBM silos, not to increase the size of existing ICBM silos “significantly,” and capped the number of SLBM launch tubes and SLBM-carrying submarines. The agreement ignored strategic bombers and did not address warhead numbers, leaving both sides free to enlarge their forces by deploying multiple warheads (MIRVs) onto their ICBMs and SLBMs and increasing their bomber-based forces. The agreement limited the United States to 1,054 ICBM silos and 656 SLBM launch tubes. The Soviet Union was limited to 1,607 ICBM silos and 740 SLBM launch tubes. In June 2002, the United States unilaterally withdrew from the ABM treaty.
Official Text: https://media.nti.org/documents/salt_1.pdf
Narrative Background on the Talks: http://www.state.gov/t/isn/5191.htm
More U.S.-Russian Nuclear Agreements: https://www.armscontrol.org/factsheets/USRussiaNuclearAgreements