The Agreement on Measures to Reduce the Risk of Outbreak of Nuclear War between the United States and the Soviet Union, signed in Washington on 30 September 1971 and still in force. Its Article 3 commits each party to notify the other immediately in the event that its missile warning system detects unidentified objects, or in any case where interference with those systems could create a risk of nuclear war.
Why it appears in the UAP literature
It is a primary document, not an anecdote, and it is the strongest checkable item in the pattern that links unidentified objects to nuclear infrastructure, a pattern that otherwise runs on incident reports such as Malmstrom AFB 1967 and on what servicemen have said afterwards. What the article establishes is that both governments treated unidentified radar returns over nuclear warning systems as a standing hazard worth a treaty clause.
What it does not establish
The clause is about warning-system ambiguity and the risk of misreading it, and it says nothing about what any unidentified object was. Read as evidence of a phenomenon rather than of a procedure, it proves less than it is often asked to.
Connections
Nuclear Interference · Malmstrom AFB 1967 · Imminent · Robertson Panel