Are you on drugs or something? American troops never “fled Vietnam”. US and other SEATO troops left peacefully after the PRVN signed the Paris Peace Accords ending the Vietnamese War with a victory by SEATO forces. The fighting was over, the VC were exterminated and the NVA was defeated on both the battlefield and economically. The Soviets totally rearmed and retrained the remains of the NVA from a light infantry/guerrilla fighting force into a modern, armor-heavy combined arms army AT NO CHARGE to the People’s Republic of Vietnam. The PRVN then started a new war and conquered the Republic of Vietnam. It was the Vietnamese clinging to those helicopters fleeing your “liberators”.