Answer:
Communists spread from People Republic of China to North Vietnam in 1950s. Without American intervention into Vietnam, the red wave must have dominated the whole Southeast Asia countries such as Thailand, Malaysia and Singapore. With American anti-communist policies at that time, the region was saved when the communists were at its peak. On the other hand, Vietnam war and Cambodia war had exhausted and eventually leaded to the collapse of the Soviet Union.
Step-by-step explanation: