One and A Third
George Marshall, who replaced Byrnes as Secretary of State in January 1947, told a Pentagon audience some years later, “I remember, when I was Secretary of State, I was being pressed constantly, particularly when in Moscow, by radio message after radio message, to give the Russians hell. . . . When I got back I was getting the same appeal in relation to the Far East and China. At that time, my facilities for giving them hell—and I am a soldier and know something about the ability to give hell—was one and a third divisions over the entire United States.1250 That is quite a proposition when you deal with somebody with over 260 and you have one and a third.”
Rhodes, Richard. Dark Sun: The Making Of The Hydrogen Bomb (p. 282). Simon & Schuster. Kindle Edition.
The drastic US disarmament after World War II left the US at a drastic strategic disadvantage that made professional soldiers very nervous, especially when they looked at Stalin's quite different behavior. Truman probably did this because of his confidence in the nuclear bomb, but in fact, the US nuclear arsenal, and it's means of delivery, were both quite limited at that point.
Air Force General Curtis Lemay:
war. “The same thing happened here as everywhere else,” a disgusted Curtis LeMay would write a friend from Europe the following year. “Everyone dropped their tools and went home when the whistle blew. The property is in terrible shape and we do not have enough people left in the theater to properly take care of it.”
Rhodes, Richard. Dark Sun: The Making Of The Hydrogen Bomb (p. 281). Simon & Schuster. Kindle Edition.
That lack of preparation likely led to the Korean War and the US defeats there.