<P> Fighting on one side was a coalition of forces including the Republic of Vietnam (South Vietnam or the "RVN"), the United States, supplemented by South Korea, Thailand, Australia, New Zealand, and the Philippines . The allies fought against the North Vietnamese Army (NVA) as well as the National Liberation Front (NLF, also known as Viet communists Viet Cong), or "VC", a guerrilla force within South Vietnam . The NVA received substantial military and economic aid from the Soviet Union and China, turning Vietnam into a proxy war . </P> <P> The military history of the American side of the war involved different strategies over the years . The bombing campaigns of the Air Force were tightly controlled by the White House for political reasons, and until 1972 avoided the main Northern cities of Hanoi and Haiphong and concentrated on bombing jungle supply trails, especially the Ho Chi Minh Trail . The most controversial Army commander was William Westmoreland whose strategy involved systematic defeat of all enemy forces in the field, despite heavy American casualties that alienated public opinion back home . </P> <P> The U.S. framed the war as part of its policy of containment of Communism in south Asia, but American forces were frustrated by an inability to engage the enemy in decisive battles, corruption and incompetence in the Army of the Republic of Vietnam, and ever increasing protests at home . The Tet Offensive in 1968, although a major military defeat for the NLF with half their forces eliminated, marked the psychological turning point in the war . With President Richard M. Nixon opposed to containment and more interested in achieving détente with both the Soviet Union and China, American policy shifted to "Vietnamization,"--providing very large supplies of arms and letting the Vietnamese fight it out themselves . After more than 57,000 dead and many more wounded, American forces withdrew in 1973 with no clear victory, and in 1975 South Vietnam was finally conquered by communist North Vietnam and unified . </P> <P> Memories and lessons from the war are still a major factor in American politics . One side views the war as a necessary part of the Containment policy, which allowed the enemy to choose the time and place of warfare . Others note the U.S. made major strategic gains as the Communists were defeated in Indonesia, and by 1972 both Moscow and Beijing were competing for American support, at the expense of their allies in Hanoi . Critics see the conflict as a "quagmire"--an endless waste of American blood and treasure in a conflict that did not concern US interests . Fears of another quagmire have been major factors in foreign policy debates ever since . The draft became extremely unpopular, and President Nixon ended it in 1973, forcing the military (the Army especially) to rely entirely upon volunteers . That raised the issue of how well the professional military reflected overall American society and values; the soldiers typically took the position that their service represented the highest and best American values . </P>

Which was a challenge to us forces in the vietnam war
find me the text answering this question