A counterfactual nuclear precedent in Korea and the Cold War

How would the world change if President Douglas MacArthur used nuclear weapons in Korea and a successor considered doing the same in Vietnam?

The precedent could normalize nuclear use in limited wars, pushing other states toward their own weapons or prompting an early treaty against tactical use.

The scenario assumes that Roosevelt survives to retire in 1948 and Douglas MacArthur subsequently becomes president. It then considers the consequences of nuclear attacks in Korea and a later president contemplating their use in Vietnam. If nuclear weapons became an accepted means of settling limited wars, other governments could invoke the same precedent. The discussion presents faster proliferation and an urgent treaty against tactical nuclear use as competing possible responses. The panel also connects the Korean scenario to attacks near the Chinese border and the danger of wider escalation. These are proposed consequences within an alternate history.