Do you mean China? So, just to frontload this - I don't think China or any Marxist-Leninist states managed to be properly communist, outside of symbolism. There's material reasons for that, too, mostly that the cycle of capital accumulation from labour -> reinvestment into productive forces continued in an exploitative way. Both Mao and Stalin wrote things trying to justify that dynamic persisting, Mao's most damning comment comes from a footnote on a document from 1953, which can be found as "On State Capitalism" on marxists.org. Stalin meanwhile wrote "Economic Problems of Socialism in the USSR", which has intersting stuff like "The Law of Value Under Socialism", and was very influential in China.

But at the time of the Chinese Civil War and Mao's faction winning out, the US simply wasn't the powerhouse of international meddling it was, yet. Even so, western allies tried to focus their support on the Chinese Nationalists and KMT, but they proved to be too incompetent and disorganised at the time. When the US started to court the People's Republic of China again much later, it was because of the conflict between the Soviet Union and China, as well as there being a huge market for industrial and consumer goods, as well as for investing accumulated (dead) capital beckoning.

Point being: It's a bit of a fallacy to imagine the US as this omnipotent international imperialist, especially before the Cold War. Not that they don't do a lot of meddling, but they aren't able to just do anything to anyone everywhere (even though secret services, be it CIA, FSB or Mossad - they will always want you to believe in their omniscience and omnipotence).