1) why did the ussr and the us enter a period of detente? explain clearly and whoever explains the best will be awarded and marked as the brainliest

Détente ended after the Soviet intervention in Afghanistan, which led to the United States boycott of the 1980 Olympics in Moscow. Ronald Reagan's election as president in 1980, based in large part on an anti-détente campaign, marked the close of détente and a return to Cold War tensions.