Tony Polson wrote:

The US-led coalition in Korea was being vanquished until the US
threatened to use nuclear weapons in a first strike. Without that
threat, you would have been in the sea.

When you're wrong Polson, you pull no stops.

The turning point was when enough US Army forces arrived for the Inchon
invasion to be mounted, cutting off the NK forces in the south from
their supply lines in the north and squeezing them between X-corps and
the breakout forces from the Pusan perimeter (that the Americans held
despite overwhelming odds prior to the buildup of forces). The Pusan
perimeter forces that the Americans had held were augmented by British,
Canadian and other forces 2 weeks prior to the breakout (mid-Sept). The
Americans had been held there since July.

That began the re-taking of the peninsula.

Truman threatened the use of nuclear arms only after the Chinese came
across the North Korean border from China. This was long after the war
had moved north of the 38th parallel.

It wasn't the threat of nuclear arms that led to the Pusan breakout, it
was many things including the aid and the support of the Brits.

Odd you don't know that.