Answer:
The United States was interfering in another nation’s civil war.
Step-by-step explanation:
The Vietnam war was a civil war fought in the asian countries of North Vietnam and Vietnam, was an undeclared war from 1955 to 1975, a war that lasted 19 years and that had both sides of the conflcit suported by communists and anti-communists countries, it ended with the Paris Peace Accords and the result was North Vietnam, Laos and Cambodia becoming communists countries, these three were backed up by China, and the USSR, while south vietnam was backed up by USA, Australia, the Phillipines and other anti-communists allies.