One event is the passage of the SALT I treaty, its full name being Strategic Arms Limitation Talks Agreement which was a treaty designed to limit the nuclear powers of countries. The idea behind it was that they would freeze their intercontinental missile production. It was allowed to build submarines only if the same number of missiles becomes dismantled.
Another event is the passage of the Anti-Ballistic Missile Treaty which was another treaty where the United States and the Soviet Union reduced the tensions between the two countries. According to the treaty, both sides would be allowed to have only two anti-ballistic missile complexes and each complex would be limited to a 100 missiles.