Space Race:

In May 1972, President Richard M. Nixon and Soviet Premier Leonid Brezhnev negotiated an easing of relations known as detente, creating a temporary "thaw" in the Cold War. In the spirit of good sportsmanship, the time seemed right for cooperation rather than competition, and the notion of a continuing "race" began to subside.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". Which two world leaders had negotiations that relieved the Cold War?
Richard M. Nixon and Soviet Premier Leonid Brezhnev