What if the offer had been accepted? I don't see how they'd have had any appreciable military impact on the war, but I think the political impact - especially later, when Communist China intervened - would have been huge. Remember that, at the time, the Republic of China was still internationally recognized by virtually all non-Communist countries; it held China's UN seat.The US Army History Center for Military History said:
It's quite possible, of course, that this might have changed later...