WILLIAM BROYLES served in Vietnam in 1969 and 1970 with the rank of lieutenant, leading a Marine platoon in combat for part of his hitch and spending the rest of it behind the lines at Da Nang as aide to a general. Unlike many others who served there, when he returned to the United States he managed to get about the business of a normal civilian life, first as the founding editor of The Texas Monthly and then, briefly, as editor of Newsweek. But the war continued to haunt him, and in the fall of 1983 he asked permission to visit Vietnam: "I wanted to do what no American veteran had ever done: return to Vietnam and write about the people we had fought against. For me the war had never really ended. If I could meet my enemy in peace, perhaps it would finally be over."

A year later the Vietnamese granted his request; he spent a month in that country, visiting Hanoi and Saigon -- hardly anyone calls it by its new name, Ho Chi Minh City -- and various parts of the countryside, Da Nang included. The result is Brothers in Arms, a thoughtful if relatively minor addition to the literature about Vietnam. The book is part war memoir, part journalistic report on the new Vietnam, and it is most interesting as the latter. Though Broyles' war experiences certainly are not to be taken lightly, his account of them is of a piece with, and largely indistinguishable from, the many other Vietnam memoirs already published. But no other Vietnam veteran has gone back and, from the perspective of one who knew the country in wartime, written about it at peace; this Broyles has done, and done it very well.

What he found was a country wretchedly poor on the one hand, yet cheerfully determined to improve itself on the other. Though reminders of the war were everywhere -- not merely in the landscape, but in mutilated bodies and broken lives -- resentment against the United States was astonishingly low. "I expected at best a mixture of curiosity and hostility," Broyles writes. "Instead I was met with an eerily perfect hospitality. It was as if some giant switch had been thrown and everyone, from government ministers to peasants, suddenly stopped fighting Americans and began courting them. War? What war? We are friends, friends, friends."

Two years ago, as now, Vietnam was officially an ally of the Soviet Union, but apart from reflexive expressions of communist orthodoxy, Broyles found little liking for the cumbersome Russians. An acquaintance "taught me the single most useful Vietnamese phrase I learned, the one that brought smiles and affection and opened doors for me everywhere: 'Khong phai Lien Xo' -- 'I am not a Russian.' " He tried out the phrase in a cafe packed with "young Vietnamese soldiers in the uniform of my former enemies," with this result: " 'Khong. Toi nguoi My,' I said. 'No, I'm an American.' At once everyone's eyes lit up and their faces broke out in big grins. The soldiers kept patting me on the back and putting their arms around me. They insisted I try on their helmets and caps with red stars on them. . . . They kept repeating the same phrases: 'America number one! Russian number ten!'; and 'America tot! Tot lam!' ('America good! Very good!')"

This widespread and evidently genuine friendliness seems to be a manifestation of the refusal by the Vietnamese to dwell on the past: they may hope to learn from it, but they decline to be obsessed by it. This was true of both civilians and military veterans, whether Viet Cong or North Vietnamese. The several North Vietnamese generals with whom Broyles met greeted him cordially and talked with him candidly, though they did not spare him withering comments on American military strategy and tactics. Everywhere, Broyles found openness, endurance and resilience:

"The Viet Cong veterans talked with me for hours, their eyes and their voices apparently untroubled by doubt or guilt about what blood might have been on their hands, and unmarked with anger or bitterness about what blood might have been on mine. They did not look into their selves and see angst or guilt or confusion, if they looked into their selves, in our Western self-infatuated way, at all. They had done their duty, like everybody else. For them the war was long, bitter, terrible -- and over. The past is past, they kept saying to me. They were sustained then, and are now, by simple ideas, believed without question. Nothing is more important than independence and freedom. Life does go on."

BUT FOR AMERICA, and for the American veteran in particular, such calm reconciliation with the past is not so speedily accomplished. Not merely are we in the West more prone to elaborate introspection, but, as Broyles was repeatedly reminded, for us the war cannot be seen in terms of simple, unambiguous ideas. The Vietnamese may regard the war as a struggle for independence and unification that they were destined to win, but an American veteran remembers other things: a fighting force manned largely by the underprivileged and ill-educated, from which the more fortunate managed to escape; hostility at home, especially among the soldiers' own generation, to the war and those who fought it; a military high command unable to grasp the realities of guerrilla warfare; a civilian administration that pursued the war long after the Tet Offensive had destroyed popular support for it.

This prolongation of the war past 1968 was accomplished at the cost of more than 25,000 American lives and those of hundreds of thousands of Vietnamese. It is this that Broyles, returning after a decade and a half, found so pervasive: the sense "of everyone who had died unremembered and unnoticed in Vietnam," of "all the people who had died such anonymous, pointless deaths here." These are not the words of a dogmatic antiwar protester, but of a man who entered the armed services out of a sense of obligation and who retains a strong loyalty to the men with whom he fought; back in Vietnam, though, he was reminded primarily of the war's terrible wastefulness and its irredeemable cost, to Vietnamese and Americans alike. That the Vietnamese refuse to dwell on this is a tribute to their character and singlemindedness, but Americans -- whose motives and actions were far more ambiguous -- cannot get off so lightly. Broyles' thoughtful memoir is yet another reminder that Vietnam will not soon stop haunting us.