why did vietnam war start

The Vietnam War started primarily due to the struggle between communist North Vietnam and non-communist South Vietnam following the country's division in 1954. The conflict escalated as the United States intervened to prevent the spread of communism in Southeast Asia, motivated by Cold War fears and the "domino theory," which predicted that if one country fell to communism, neighboring countries would follow. The U.S. initially provided funding and military aid to South Vietnam and later committed troops after alleged attacks on U.S. naval vessels, which led to the Gulf of Tonkin Resolution granting broad war powers. The war was rooted in Vietnam's desire for independence from foreign control, Cold War geopolitics, and the Vietnamese civil war between communist and anti-communist forces.