Manchukuo

Manchukuo, officially the Republic of Manchuria, is a country in East Asia.

Independence
On 1945, The Soviet Union occupied Manchuria until 1946, when they gained independence, establishing the Republic of Manchuria. It is not a communist nation however. On 1947, it is close friend with United States. On Chinese Civil War, they helped Republic of China.

Sino-Manchukuo War
When the PRC won on 1949, they want to take Manchuria. So Manchuria was attacked, but PRC was quickly defeated.