It seems I recall that MacArthur wanted to take the fight into China.. He may have said something to the effect that he already had the equipment and manpower on the ground so why not finish the job.. Truman disagreed.. (?)
Re “we already have the men equipment”. That was Patton in Europe not MacArthur in Japan.
MacArthur “beef” with Truman was over how to best use Formosa during the Korean War. Truman was an idiot that killed a lot of American GIs.