(1) in fighting the Vietnam War, the US protected Thailand, Malaysia, Indonesia, and the Philippines from being overrun by communist insurgencies; and
(2) and that by changes in tactics and strategy, the US under Gen. Creighton Abrams had the guerrilla war won until a Democratic Congress cut of assistance to South Vietnam. This led to North Vietnam defeating the South through a conventional invasion.
Those points seems correct but do not necessarily mean that the US war effort was strategically sound or at a reasonable cost relative to any benefits.
Look at Vietnam today. We have great relations with them. And their economy is no longer controlled by the government and they have opened themselves up to the market.
So if other countries wanted to become communist in the '70s, let them. It was unlikely to prevail in the long term.