Mikhail Gorbachev, the last president of Soviet Union was actually the one that stabilized relations with United States, and during his presidency the Cold War ended and Soviet Union disappeared as a country. He signed a couple of important documents, especially with Ronald Reagan, which ended the nuclear race.
Explanation:
Gorbachev's period was a turbulent one. Famous crisis in the Soviet Union led to disappearance of that country. Still, Gorbachev realized the situation and wanted to improve relations with the States which were pretty tight. Later on, for his work Gorbachev received Nobel Prize for peace.