The United States stumbled into a shaky government inthe 1950s and the unvarying policy of every subsequent administration was to do what was necessary to prevent the collaspse of that government. They were doing so not because they anticipated victory but because they saw no alternative. However high the costs of intervention , they believed the cost of not intervening, of allowing South Vietnam to fall, would be higher. Only when the national and internationalp political situation had shifted to the point where was possible for American policymakers to reassess the costs of containment to conclude that the cost of continuing the commitment-was it possible for the United States to begin disengaging.
This solution offers an explanation as to the background of the US intervention into Vietnam.