Answer:
500,000.
Explanation
The Vietnam war was fought between North Vietnam and South Vietnam. The North Vietnam was a communist country and wanted the spread of communism to South Vietnam. The United States didn’t want this and supported South Vietnam through providing troops and war equipment for the war.
At the peak of the Vietnam War, the number of American troops in Vietnam was approximately 500,000. The US and South Vietnam lost the war and the communist spread to South Vietnam was achieved.