Dixie Mission

The Dixie Mission' was an American mission to the liberated areas in China:

"The United States Army Observation Group, commonly known as the Dixie Mission, was the first U.S. effort to establish official relations with the Communist Party of China and the People's Liberation Army, then headquartered in the mountainous city of Yan'an. This mission was launched on 22 July 1944 during World War II, and lasted until 11 March 1947."

Despite friendly relations on the ground in Yan'an, the final decision by the United States was to not ally with the revolution.