Among the other legacies it left us, Vietnam bequeathed a legacy of lies. Some of the key lies are documented tonight in a sober, hard-hitting "NBC News White Paper" called "Vietnam, Lessons of a Lost War," with Marvin Kalb, at 10 on Channel 4. Not a contemplative elegy like Walter Cronkite's Thursday night hour on CBS, "Lessons" takes a cold, clear look at pivotal wrong turns and miscalculations that helped make Vietnam the debacle it became.

If anything, this NBC News report is a follow-up to the history-making 1982 CBS News documentary, "The Uncounted Enemy: A Vietnam Deception," which used a specific case of falsification to symbolize all those that pulled us into the swamp. In the controversy and litigation over that broadcast, its daring and its excellence have been overlooked.

Well before Watergate, we are reminded, we were being misled by a president. "Lyndon Johnson lied both to the American people and to himself," says Larry Berman, an antiwar activist then, a political scientist now, on tonight's NBC report. He tells Kalb, "Johnson lied and deceived the American people about the nature . . . of the extent of the Vietnam War, about his expectations for military victory and his expectations for what we reasonably thought we could have accomplished in Vietnam."

James Stockdale, a retired admiral who was a fighter pilot during the war, recalls the sinking feeling he got when LBJ ordered air attacks against North Vietnam on baldly false pretenses, alleged "provocation" from the North that led to the Gulf of Tonkin resolution and that former undersecretary of state George Ball now concedes may have been "simply a confusion of radar signals."

"You have to be there to realize that the world has turned a corner," Stockdale tells Kalb. "I said, 'We are now locked in the Vietnam war, there's no question about it' . . . Just the mere fact that it was an illegitimate birth made that war a bastard."

LBJ's secretary of defense, Robert S. McNamara, emerges a bad guy turned good guy in this report. Although McNamara, as usual inscrutable, refused to be interviewed, NBC News obtained McNamara's secret memos to Johnson, which indicate his growing disillusion and his quiet attempts to dissuade the imperious LBJ from his ruinous course. Kalb says that at first "McNamara masterminded the case for escalation," and surreptitious escalation at that, but that as early as Nov. 30, 1965, his memos were indicating he was "increasingly driven by doubts" about the war, despite his "gung-ho" public posture.

A year later McNamara was urging compromises and supporting a coalition government, and Lyndon Johnson turned huge deaf ears. There is then great poignance to news footage of McNamara's farewell appearance upon his resignation and his remarks to Johnson: "Mr. President, I cannot find words to express what lies in my heart today. And I think I'd better respond on another occasion." But when, oh when, is that occasion to be?

Dean Rusk is also among those interviewed for the program, which also examines the aftereffects of the Tet offensive, a subject better covered in "Uncounted Enemy." It took high gall for Kalb to say that after Tet "some of America's most trusted and responsible newscasters" decided it had been a U.S. defeat and then cite the late Frank McGee, in NBC News footage, as the chief example. Everybody knows it was Walter Cronkite on CBS whose opinions carried the most weight -- with the country and with the White House.

Kalb is a leaden screen presence, which does not detract from his abilities as a reporter, and a mediocre writer, which does. Before showing the oft-seen footage of the Viet Cong prisoner being executed at point-blank range on a Saigon street, he fumblingly asks viewers, "Do you remember this scene?" Yes, Marvin; we're not dolts.

But there are compensating deft touches. As Kalb is talking about how radically U.S. military officials underestimated the tenacity of the enemy, there is a dissolve from the Vietnam Veterans Memorial to North Vietnam's own version of that memorial, the names still being painted on. Racist epithets about the Vietnamese implied "they could never quite measure up to us," Kalb says. "Well, they measured up. And more."

A strong, solid report, "Lessons" reminds us, as no network documentary since "Uncounted Enemy" has, that there is cause to be more than sorrowful about Vietnam. There is cause still to be angry. The words of Stockdale, talking about the "retaliation" after Tonkin, have the most sting: "I'm no whistle-blower. I'm a soldier, and it didn't give me any conscience pangs to go ahead and carry it out at the time. It's not my conscience that irks me. It's just the stupidity of it that irks me. And let's hope we never do that again."