Even by the mid-1950s, the country was often treated less as a nation with its own unique set of political issues, and more as a generic Asian theatre of war, in which the righteous battle against communism could be played out. China Gate (1957) is an early example of this trend. Rather more depth of thought went into the making of The Quiet American (1958), in which Michael Redgrave played the British journalist and cynic, Fowler, while Audie Murphy played Pyle, the eponymous "hero" of Graham Greene's novel. To Greene's chagrin, Pyle was depicted not as a representative of the American government, but of a private aid organization - something which the author felt blunted his anti-American message.

With American troops duly deployed by 1965, it was only a matter of time before John Wayne produced his patriotic and monumentally bad The Green Berets (1968), which depicts American soldiers in spotless uniforms fighting against no less a threat than total "Communist domination of the world". But the war was a much dirtier affair than The Green Berets made it seem, and as popular support for the conflict soured, a raft of exploitation movies was churned out, in which the mental scars of Vietnam provided topical window-dressing to improbable tales of martial arts, motorbikes and mayhem. At best, vets were treated as dysfunctional vigilantes acting beyond the pale of society - most famously in Taxi Driver (1976), which has Robert De Niro's disturbed insomniac returnee, Travis Bickle, embarking on a one-man moral crusade to purge the streets of a hellish New York.

Only in 1978 did Hollywood finally pluck up courage enough to confront the war head-on, and so aid the nation's healing process. Movies no longer sought to make sense of past events, but to highlight their futility, and audiences were confronted by disaffected troops seeking comfort in prostitution and drug abuse, along with far more shocking examples of soldiers' fraying moral fibre. Coming Home (1978), which cast Jane Fonda as a military career-man's wife who falls in love with a wheelchair-bound veteran (Jon Voight), was significant for its sensitive consideration of the emotional and physical tolls exacted by the war. Similarly concerned was The Deer Hunter (1978), in which the conscription of three friends fractures their Russian orthodox community in Pennsylvania. The friends' "one-shot" code of honour, espoused on a last pre-Vietnam hunting trip, contrasts wildly with the moral vacuum of the war, whose random brutality is embodied in the movie's central scenes of Russian roulette. But for all its power, The Deer Hunter is marred by overt racist stereotyping of the Vietnamese. Francis Ford Coppola's hugely indulgent but visually magnificent Apocalypse Now (1979) rounded off the vanguard of postwar Vietnam combat movies. It was described by one critic as "Film as operaa?¦ it turns Vietnam into a vast trip, into a War of the Imagination". Coppola totally mythologizes the conflict, rendering it not so much futile as insane.

The precedent set by Coming Home of sympathetic consideration for returning veterans' mindsets spurred many movies along similar lines in subsequent years. These focused on the disillusionment and disorientation felt by soldiers coming back, not to heroes' welcomes, but to indifference and even disdain. One of the first was First Blood (1982), which introduced audiences to Sly Stallone's muscle-bound super-vet, John Rambo. Alan Parker's Birdy (1984) and Oliver Stone's Born on the 4th of July (1989) reiterated the message of stolen youth.

During the 1980s, Hollywood attempted, bizarrely, to rewrite the script, in a series of revisionist movies. Richard Gere had made the armed forces hip again in 1982's weepie An Officer and a Gentleman ; and a year later the first of an intriguing sub-genre of films hit cinemas, in which Americans returned to Vietnam, invariably to rescue MIAs, and "won". Uncommon Valor (1983), a rather silly piece about an MIA rescue starring Gene Hackman, kicked things off, closely followed by Missing in Action (1983), in which Chuck Norris karate-kicks his way towards the same resolution. The mother of them all, though, was Rambo: First Blood, Part II (1985), in which the hero of First Blood gets to settle some old scores.

The backlash to the patent nonsense of the revisionist films came in a series of shockingly realistic movies which attempted to reveal the real Vietnam, routine atrocities, indiscipline and all. There are no heroes in these GI's-view movies, only fragile, confused-looking young men in fatigues. In Platoon (1986), Oliver Stone, himself a foot-soldier in Vietnam, shows the circumstances under which it was feasible for young American boys to become murderers of civilians. It powerfully conjures the paranoiac near-hysteria spawned by fear, confusion, loss of motivation and inability to discriminate between friend and foe. In Hamburger Hill (1987), the image of an entire generation stumbling towards the maws of death is strengthened by the fact that the cast includes no big-name actors - the men who fall are neighbours, sons or brothers, not film stars. Stanley Kubrick's Full Metal Jacket (1987) picks up this theme of the war's theft of American youth with a brutal drill-sergeant who sets about expunging the soldiers' humanity.

Vietnamese people have mostly been noticeable by their absence from Hollywood films, or have been viewable only through the filter of blatant stereotyping. Heaven and Earth (1993), the final part of Oliver Stone's Vietnam trilogy, went some way towards rectifying this imbalance. Its depiction of a Vietnamese girl's odyssey from idyllic early childhood to the traumas of life as a wife in San Diego acts as a timely reminder that not only Americans suffered during the struggle.

Meanwhile, Tran Anh Hung has emerged as Vietnam's pre-eminent domestic film director. Cyclo (1996), his grisly tale of murder and prostitution on Vietnam's mean streets, contrasted hugely with Scent of Green Papaya (1993), the nostalgic colonial period piece that made his name.