 Regardless, U.S. and South Vietnamese troops successfully fought off the attacks during the Tet Offensive, and the communist forces took heavy losses, but the ferocity of the assault shook public confidence in Westmoreland's previous assurances about the state of the war.Political debate and public opinion led the Johnson administration to limit further increases in U.S. troop numbers in Vietnam.Nine months afterward, when the My Lai Massacre reports started to break, Westmoreland resisted pressure from the incoming Nixon administration for a cover-up, and pressed for a full and impartial investigation by Lieutenant General William R. Peers.