World war 2 set the stage for the Korean and Vietnam war mainly due to the fact that nuclear weapons were used on Japan. This caused much tension between the United States and many other countries. Especially communist Russia.
During World War 2, Vietnam had been run by the Japanese, after the bombing and loss of the war, they retreated, and the people of Vietnam established their own government, however at the end of the war. The allies gave South Vietnam to the French, and left North Vietnam to the Communist Chinese.
After World War 2, Korea had split into 2 zones of occupation. The United States controlled the South and the Soviets owned the North. Just 2 years after World war 2 the Cold War had started which stirred up more tension between the North and the South. Eventually in 1950, North Korea invaded the South and started the Korean War