Uncle Joe managed to send Mao what he could, when he could, to keep his operation in business.
Old Vinegar Joe Stillwell, was one of the best generals in WWII. He fought bravely against the Japs with hardly any supplies. His job was to beat the Japs. I do not blame Stillwell for this situation, he was just a soldier doing his job. I blame Roosevelt. Roosevelt was blind to the commie threat. Patton saw the writing on the wall, he knew that the war in Europe was not over with the defeat of the Germans. He told us to continue the fight against the commies. He warned us of what was to come and we are in trouble today because we did not heed his advise.
Chiang Kai-shek was caught between two enemies at the same time. Chiang could have defeated Mao, if he had help from the US. Unfortunately, The US did not take the commies seriously until it was to late.