I'm working on a TL that starts with a delayed Korean War that goes very badly for the United States, and I wanted to see if this passed the smell test.
The PoD is in 1949, with the early death of Stalin. With the Soviet leadership fighting over the succession, the Korean War doesn't happen in 1950. As a result, Louis Johnson is in charge of the Department of Defense for two more years, with all the budget-cutting that implies, and with the international situation seemingly stabilizing the Selective Service Act is allowed to expire in 1950 instead of being renewed.
When the North Koreans cross the border in 1952, the US Army is in much worse shape: they're in the middle of their second transition from a draft force to a volunteer force in five years, and the budget cuts mean their existing supplies of arms and ammunition are much smaller. Then, the North Koreans get lucky and capture Syngman Rhee in their drive south (I think I remember reading that they came within a few hours of doing that IOTL, but correct me if I'm wrong). It becomes clear that the Pusan Perimeter will not hold, and Truman orders the use of an atomic "demonstration shot" off the coast of North Korea to force them to back down.
So, what do you think? I know the usual Korean-War-goes-bad scenario is after the Chinese enter the war, but it's difficult to get the timing on that to work with some other things I want to happen.