If we knew then what we know now, we should have just let the Japs have it.
The CCP and the Nationalists Chinese worked hard to fight each other, wanting the USA and allies to defeat the Chinese, while the Chinese worked to defeat each other.
There was considerable sympathy for the Chinese Communists in the USA, especially in the State Department.
After WWII, McCarthy was able to get rid of some of the Chinese Communist sympathizers in the State Department, but, ultimately, the US Media, dominated by Progressives, got rid of Senator McCarthy.