THE KILLING FIELDS," based on an article by New York Times correspondent Sydney Schanberg, is the most powerful study of the Vietnam era since "Apocalypse Now." The subject is war and more -- the nightmares that make men friends, then shatter those friendships to smithereens.

Schanberg and his assistant, Cambodian reporter Dith Pran, separate when the Asian wars spill into Cambodia and the Khmer Rouge take Phnom Penh. The foreign press is evacuated, but despite Schanberg's efforts, his friend Pran is left to the mercies of the sadistic new rule. The film follows Schanberg's search and Pran's struggle, a fearful odyssey that lasted 41/2 years.

An introspective Sam Waterston stars as the serious, thrill-seeking, truth-telling Schanberg; newcomer Haing S. Ngor, a Cambodian refugee who is not a trained actor, plays Pran. His performance is as moving as any because it is so accepting, so humble and so stoic. In an emotional scene between these two terse men, Schanberg asks Pran to leave the country with the American nationals. Pran agrees to send his family, but says, "You know me, Sydney. I'm a reporter like you, and I'm not leaving."

The cast is uniformly excellent just as the film is uniformly intense, especially after the Khmer Rouge begin their blood-red reign. But the violence is less than that in a horror film, and while often grueling, is appropriate rather than gratuitous.

Some of the most potent images, however, are the less gruesome ones: a toddler with hands over ears to close out the mortar fire; the choppers, like Francis Ford Coppola's, with their fierce blades; Coke cartons, signs and bottles as recurring omens of death.

This is an honorable, honest film that does not hide from the consequences of claymore mines and B-52 bombers. It is no Gene Hackman fairytale. It examines the corruption of power of both the Khmer Rouge and the men of the Nixon administration, all of it deadly to the small, fragile-looking Cambodian people left behind without allies to deal with those who reap the Killing Fields.

Roland Joffe's direction is gripping, unflagging, if sometimes ragged. But the flaws strengthen the film, give it a more realistic edge, which truly reflects the time and captures the joy of forgiveness and friendship refound. THE KILLING FIELDS -- At the Avalon, the K.B. Montgomery Mall and the Springfield Mall Cinema.