POD: The 1991 Soup coup d'etat attempt succeeds. Gorbachev and the reformists are banished behind closed doors, while hardline Marxist-Leninist types decide to prevent the further dissolution of the Soviet sphere of influence.
Attempts to crackdown on the independence of these new republics is met with fierce international opposition. NATO pledges to defend the new republics if the Soviets do not back down, hoping a game of chicken with the USSR will cause the hardliners to blink first. They don't. The Soviet Union launches a full scale invasion of various regions in rebellion and harshly put down resistance within Russia and various SSRs. The United States thus coordinates an anti-communist blockade and embargo to squeeze out the Soviets.
The blockade leads to a Soviet attack on NATO positions in Europe, which by the summer of 1992 has lead to an all out war between the United States and Soviet Union. Nuclear weapons are used, though not indiscriminately, and the war itself will see millions on both sides die. The Soviet Union ultimately falls with the razing of Moscow and the subsequent collapse of the Politburo in 1997, with NATO forces just outside major population centers in Western Russia...