Did the U.S. lose the Vietnam war?
In order to know whether the U.S. lost the Vietnam war or not, it’s wise to go back and see
why the Vietnam war started in the first place.
Domino theory or containment was usually used as a justification for the U.S. involvement in Vietnam. The fact is the U.S. failed to stop the spread of Communism throughout Vietnam which led to its spread to Laos and Cambodia in 1975. However, it is arguable that the effects of the war in Korea and Vietnam that the U.S. had involved in did help the rest of South-East Asian countries such as
Thailand and Singapore stay free of communism.
Military-wise, the U.S. arguably
never lost any major battles. However, it could not stand the constantly increasing loss of American lives and the economic burden the war carried on its people and was eventually forced to leave Vietnam before the war ended. Without its direct support, South Vietnam surrendered to the North Communists and disappeared from the world map not long later.
In short, in the picture of Vietnam, the U.S. failed to defend South Vietnam against the North Communists and probably lost the war politically rather than militarily as Vietnam was far from the war of major battles. In the bigger picture of containment, the U.S. did achieve their initial goals to a certain extent.
My point is and will always be from the stand point of the military perspective. Most experts agree, had the military been given the permission of a full scale attack into north Vietnam the war would have been over in the mid 60's with just small guerilla resistance after that.