According to Greenpeace , the United States and USSR were concerned enough by accidents such as the 1961 Goldsboro B-52 crash , the 1966 Palomares B-52 crash and the Thule accident that they agreed to take measures to ensure that a future nuclear accident would not lead the other party to conclude incorrectly that a first strike was under way . Consequently , on 30 September 1971 , the two superpowers signed the " Agreement on Measures to Reduce the Risk of Nuclear War " . Each party agreed to notify the other immediately in the event of an accidental , unauthorized or unexplained incident involving a nuclear weapon that could increase the risk of nuclear war . They agreed to use the Moscow – Washington hotline , which was upgraded at the same time , for any communications
1966 Palomares B-52 crash
1966 Palomares B-52 crash
1968 Thule Air Base B-52 crash