North Vietnam invaded South Vietnam. Russia and China and to a smaller extent Cuba came alongside North Vietnam to help their cause. The United States, Canada, Australia, Philippines, and Korea aided South Vietnam in defending their sovereignty.
After the war, there was a reunification of Vietnam. So the answer is "One country".
If you're referring to the Vietnam War, then the war was mainly fought between North Vietnam and South Vietnam. North Vietnam was communist, and was supported by the Soviet Union, China, and Cuba. South Vietnam was capitalist, and was supported by the United States, Australia, the Philippines, and South Korea. Vietnam was also invaded and conquered, then colonized, by France in the 1800s.
colonized by french and invaded by mongolions
The North invaded the South and defeated them (conquered them).
The Korean War directly resulted in the US NOT INVADING North Vietnam.
The only big lesson learned was North Vietnam was not invaded. During the Korean War, N. Korea was invaded; that brought in Red China. That strategy was not repeated in the Viet War.
north Vietnam invaded south vietnma
At the begining of World War 2 they invaded Indochina (Vietnam).
North Vietnam and South Vietnam. Also, to name just a few: the USA, China, Russia, South Korea, Australia, France, and England. A great many countries fought in the Vietnam War from 1945 to 1975.
Germany invaded France during World War II.
There were some countries that were neutral during World War 2 that invaded Germany. These countries included the United States and Sweden.
NVA tanks invaded Saigon and captured that city (the capital of South Vietnam).