Answer:
Afghanistan
Step-by-step explanation:
Afghanistan.
In 1979, the Soviet Union invaded Afghanistan to support the Afghan communist government, which was facing a rebellion by Islamic fundamentalist groups. The Soviet military intervention turned into a protracted and costly conflict, as the Afghan resistance, known as the Mujahideen, received significant support from the United States and other Western countries.
The Soviet Union's military campaign in Afghanistan was marked by brutal tactics, including the widespread use of air power and the deployment of Soviet conscripts who were often ill-equipped and poorly trained. The Soviet Union's military involvement in Afghanistan lasted for over nine years and resulted in tens of thousands of Soviet casualties. The conflict also had significant economic costs, as the Soviet Union had to divert resources away from other domestic priorities to fund its military campaign in Afghanistan.
The Soviet Union's failure to achieve a decisive victory in Afghanistan undermined the morale of the Soviet military and eroded public support for the war at home. The Soviet Union's withdrawal from Afghanistan in 1989 was widely seen as a defeat, and the war contributed to the overall decline of the Soviet Union's military power and international prestige