Why and how detente collapsed in the late 1970s and the early 1980s?

Detente collapsed in the late 1970s and early 1980s primarily due to increasing tensions between the United States and the Soviet Union, driven by geopolitical conflicts such as the Soviet invasion of Afghanistan in 1979. This invasion was perceived as a direct threat to global stability, prompting the U.S. to adopt a more aggressive stance, including the suspension of arms control talks and the boycott of the 1980 Moscow Olympics. Additionally, the election of Ronald Reagan, who took a hardline approach against communism, further escalated hostilities and marked a departure from the conciliatory policies of previous administrations. The combination of these factors led to a significant deterioration in U.S.-Soviet relations and the eventual end of detente.