Which element of the Chinese Civil War would most likely suggest that the conflict was a proxy war?

The involvement of foreign powers in the Chinese Civil War suggests that it had characteristics of a proxy war. The United States supported the Nationalists (Kuomintang) with military aid and financial resources, while the Soviet Union provided support to the Communists (Chinese Communist Party). This external influence and intervention indicate that the conflict was not solely a domestic struggle, but rather a battleground for competing ideologies during the Cold War era.