what caused relations between the united states and the soviet union to begin to change in the early 1980s

Leonid Brezhnev died

Ronald Reagan became president

Explanation:

The Cold War refers to the increased hostility between the Soviet Union and the US. It arose from a strong denunciation of the Soviet Invasion of Afghanistan in December 1979. With the election of Prime Minister Margaret Thatcher in 1979 and American President Ronald Reagan in 1980, a change in Western foreign policy approach toward the Soviet Union was marked by the rejection of détente in favor of the Reagon Doctrine policy of rollback, with the stated goal of dissolving Soviet influence in Soviet Bloc countries. During this time, the threat of nuclear war had reached new heights that hadn't be seen since the Cuban Missile Crisis of 1962.

i think its the outcome of people's preferences.

location is the answer to this