When and how did detente end?

Detente, the easing of tensions between the United States and the Soviet Union, effectively ended in the late 1970s, primarily due to the Soviet invasion of Afghanistan in December 1979. This military action was perceived by the U.S. as a significant threat, leading to a re-escalation of Cold War hostilities. In response, the U.S. imposed economic sanctions, boycotted the 1980 Moscow Olympics, and increased military spending, marking a return to a more confrontational stance. Consequently, the cooperative engagements that characterized detente were largely abandoned.