Barely two months later, the Soviets constructed the Berlin Wall.

Relations warmed in the 1970s, leading to a series of agreements that slackened the nuclear arms race.

The negotiating technique of Soviet leader Leonid I. Brezhnev resembled that of Mr. Khrushchev — he would berate the Americans for not working as allies in the Middle East, say, or accuse them of sabotaging world peace. “It would be his way of testing my resolve,” President Gerald R. Ford wrote in his memoirs. “He would be curious to see if I would bend or fight back.”

As Mr. Ford was departing after their first meeting in the city of Vladivostok in November 1974, he noticed Mr. Brezhnev eyeing his Alaskan wolf coat and in a spontaneous gesture, handed it to the Soviet leader.