If Kennedy Had Lived . . . : JFK AND VIETNAM; Deception, Intrigue, and the Struggle for Power, <i> By John M. Newman (Warner Books: $22.95; 506 pp.)</i>

The Vietnam War always will be a disturbing puzzle. Why did we lose? How did we think we could win? This thoughtful, carefully documented, but sometimes overdrawn book offers both answers and troubling questions.

John Newman, an Army major and consultant to Oliver Stone’s “JFK,” focuses on the “war before the war”: the growing American advisory effort in South Vietnam from mid-1961 to the assassinations of both Kennedy and President Ngo Dinh Diem, in November, 1963. Newman portrays a bitter struggle in Washington between the Pentagon (working with Lyndon Johnson), which lied, cheated and virtually conspired to get American combat forces into Vietnam; and a skeptical Kennedy, who finally compromised by sending thousands of military advisers.

Newman’s most controversial contention--one that underlies Stone’s “JFK”--is that Kennedy realized by mid-1963 that American intervention was stymied and had to be ended. Kennedy’s 1,000 military advisers were in fact withdrawing when the assassination intervened and Johnson took power, driving us to disaster. Newman’s conclusion: Had Kennedy lived, the course of history would have changed dramatically.

But is Newman’s the Kennedy we knew, the hard-liner on Berlin and Cuba, Laos and Vietnam? Or is Newman, by focusing on selective political documents rather than ideology or personality, idealizing Kennedy? Newman’s vision of warmongering hawks--a group of conspiratorial Washingtonians whose motives he barely examines--is indeed based more on suppositions and innuendoes than evidence.

Nevertheless, at another, deeper level, Newman’s points are highly persuasive. He convincingly demonstrates that the advisory “war” failed within months, that this foreshadowed later disasters, and that no one--aside from some advisers in the field--dared to face reality.

Newman does. A military-intelligence officer, he writes as an insider who has found key documents, had them declassified, interviewed retired officers and correlated the facts. By 1962, there were few actual trainers of South Vietnamese forces. Instead, in our technological zeal we sent combat specialists who knew a lot about helicopter thrusts, aerial bombing, bigger ground operations and intelligence gathering, but almost nothing about Vietnam, its history, culture and politics.

Not surprisingly, then, none of their efforts worked, as Newman demonstrates. The Viet Cong learned how to fire at the vulnerable choppers. The bombers often hit innocent civilians with whom the guerrillas were intertwined. The South Vietnamese infantry avoided fighting, because the army--i.e, the officer corps--constituted Diem’s power base, and he feared that casualties might hurt morale: Let the Americans, those rich monkeys, do the dirty work. This is not to say that all leaders in Washington knew we were losing the war, for the military brass was careful to keep the bad news from their bosses.

* In mid-1962, Gen. Paul Harkins, the U.S. Army commander in South Vietnam, demanded that his intelligence analysts drastically chop their estimates of Viet Cong. There was anger, muttering, attempts to outflank Harkins. One captain could only reply, “None, sir” when Harkins questioned how many guerrillas this staff officer had personally seen come south on the Ho Chi Minh trail. “And that’s how many I’ll accept,” Harkins snapped back, rejecting the officer’s careful estimates of daunting numbers..

* In August, 1963, as a political crisis convulsed South Vietnam, there was talk in Saigon and Washington of a coup against Diem. With Kennedy and his top advisers out of town on a Saturday, instructions were drafted for the ambassador in Saigon by Roger Hilsman and Averell Harriman at the State Department. They demanded major concessions by Diem, on pain of transferring American support to “appropriate military commanders” should his government collapse. The message was phoned to Kennedy in Hyannisport. He agreed that it should be sent if Secretary of State Dean Rusk approved. And Rusk, in New York, agreed to do so if Kennedy and others approved. In effect, the President and his key adviser were passing the buck while subordinates took the helm. There were bitter arguments over the cable, and Kennedy told a friend, “My God, my government is coming apart.” But he did little to hold it together.

A secretary of defense wrestling with unimaginative lieutenants in a small war; a general outraging officers with his stubborn refusal to face facts; a President whose uncertainties offered free rein to quarreling subordinates: These were signs of trouble ahead--signs, Newman contends, that were ignored. Instead, “escalation” was allowed to become the goal. American troops would achieve what the Vietnamese could not.

And this was several years before most Americans knew where Vietnam was, let alone began taking positions on the war. Even in 1962, events were showing the war to be amorphous and tricky. Although Newman rightly denounces the policy-makers--especially Taylor--for their blindness, he is unaccountably generous to Kennedy, who appointed them, led them and listened to them.

That Newman, a professional soldier of 17 years’ service, could write so critical a book suggests how open the Army has become since the Vietnam disaster. And Newman is not alone. No less critical books have been published since the war by colonels Andrew Krepinevich (“The army in Vietnam”) and F. Charles Parker (“Strategy for a Stalemate”), and by retired Brig. Gen. Douglas Kinnard (“The Certain Trumpet: Maxwell Taylor and the American Experience in Vietnam”). Rather than blaming the White House or student radicals, these and other historically trained officers are raising blunt questions about the Army’s failures in the 1960s.

The toughest questions, however, concern Kennedy, that charming, intelligent, yet slippery figure. In the great struggle between peace and war that Newman presents, Kennedy represents moderation, even wisdom: Did he not restrain the hawks? And this while standing alone, gallant and unsupported?

Would that it were so. Kennedy was not as perceptive as Newman contends. A Communist victory, he feared, would trigger both a right-wing “Who Lost Vietnam?” debate at home, and further guerrilla campaigns in the Third World; there was Castro to consider.

Far from the hawk-tamer Newman paints him to be, Kennedy was often indecisive, detached and overly conciliatory, more like a British prime minister presiding over a cabinet of equals than an American President trying to master events. Would, say, Johnson or Roosevelt have complained that “My government is coming apart”? Or would either have been stunned by Diem’s assassination, a tragedy that a realistic, demanding Kennedy might have prevented? That was not his way.

Nor was it to agonize over long-term Vietnam policy. Far more likely, Kennedy would have muddled along, hoping that Averell Harriman could, somehow, pull a diplomatic rabbit out of the hat. Having triumphed over serious illness throughout his life, Kennedy had learned to trust in luck. But in Vietnam, luck wasn’t enough.

BOOK MARK: For an excerpt from “JFK and Vietnam,” see the Opinion section, Page 3.