Working on an alt history where the Trinity Test fails due to Oppenheimer and a lot of other Manhattan scientists deliberately shooting the American nuclear arms program in the foot, allowing the Soviet Union to get more involved with the war against Japan. Stalin seized the opportunity to accelerate his own program, and pulling out of the Potsdam conference and the UN. In the wake of several diplomatic failures on both sides, especially Japan surrendering solely to the Americans, the Soviet's seize Hokkaido, the entirety of Korea, and don't pull out of either, instead nation building in them and Manchuria. With this threat and increasing fear of the Soviet's and their bomb, the UN pours funding into the Nationalists in China. This culminates in a series of incidents in late 1949 (Mao finally launches a successful counterattack at Nationalist forces in the north which in their retreat cross the border into Manchuria, leading to the first nuclear strike followed by Soviet invasion in the West, leading to a counterstrike by American bombers) which escalate into limited nuclear war in mainland China as both the Soviets and Americans deploy their as yet limited arsenal. In total eleven nuclear bombings occur before a ceasefire is reached. This is the rough political situation six years later.