Explain how the spread of communism after the vietnam war differed from us strategists expectations

North Vietnam won the war against its southern opponent in 1975, unifying Vietnam into a communist nation. According to the American strategic analysts, and in accordance with the Domino Theory, the victory of communism in the Vietnam War would represent the total fall of Southeast Asia in the hands of said regime, through a contagion effect that would generate successive uprisings against the democratic regimes in the area. It was even feared that the entire corridor between China and Vietnam, and its areas of influence, would turn towards socialism.

But in the end the situation was very different: only Laos and Cambodia were part of this "contagion effect" becoming communist states, while the other countries in the region, such as the Philippines, Indonesia, Malaysia or Thailand, to cite examples, maintained capitalist-orientated governments.