The U.S. president during the conclusion of the Cold War was Ronald Reagan, who served from 1981 to 1989. His administration played a critical role in reducing tensions between the U.S. and the Soviet Union through a combination of diplomacy and military buildup. Major events such as the fall of the Berlin Wall in 1989 symbolized the end of Cold War divisions in Europe, and Reagan's policies, including the push for arms control agreements, contributed to a more favorable climate for negotiations. His leadership marked a significant shift in U.S. foreign policy that ultimately influenced the Cold War's conclusion.