What happened
The Politburo's decision to invade rested on a narrow security calculation — propping up a fellow communist government facing internal collapse — made with almost no serious assessment of the terrain, the durability of Afghan resistance, or the diplomatic cost. The war triggered a US-led grain and Olympic boycott, ended détente, and restarted a Cold War arms buildup that Soviet leaders had hoped to avoid.
Domestically, the war was fought largely by conscripts, and the Soviet government suppressed accurate casualty reporting for years — soldiers were shipped home in sealed zinc coffins ("gruz 200") with families frequently told only that their sons had died "performing their international duty," without details.