The homecoming news conference of the four Vietnam combat veterans who visited Vietnam over Christmas was a stormy affair. It could hardly have been otherwise.

The trip stirred the acrimony and division that attends any Vietnam-related enterprise. Robert O. Muller, the sharp, young paraplegic who heads the Vietnam Veterans of America, was variously hailed as a healer of the wounds of war and a dupe of the master manipulators in Hanoi.

His motives for the excursion, which was his idea and was financed by Penthouse magazine, were questioned, some seeing it as a grandstand play to fatten the ranks of his puny organization. One veteran at yesterday's New York press meeting shouted that Muller was "a total disgrace to everyone of us who served in Vietnam."

The Veterans of Foreign Wars condemned the trip in advance. The American Legion questioned its advisability. The National League of POW-MIA Families reported calls from VVA members who were defecting to protest what one called "kowtowing to the North Vietnamese leaders."

What gave particular offense to some was a wreath-laying ceremony at the tomb of Ho Chi Minh, which one exercised veteran called the equal of "urinating on the American flag."

But Rep. G.V. (Sonny) Montgomery, the Mississippi Democrat and conservative who heads the House Veterans Affairs Committee and has made 12 trips to Vietnam, had "no problems" with it, except for the visit to Ho's mausoleum.

"The way they handled themselves it seems like they were trying to gather information on Agent Orange and the MIA, which are the key interests that we have in that part of the world," said Montgomery from his Mississippi office.

The New York and Washington offices of the VVA reported overwhelming support for the trip. "It's about time," many vets said. But Muller and his companions, Michael Harbert, John Terzano and Thomas Bird, came in for some flak from the brothers for "talking about Agent Orange with the Vietnamese, when they're using chemical warfare in Laos."

Muller, speaking on the telephone after the news conference, was unrepentant:

"We have no apologies. We know we've got people who want to continue this war for decades. We felt there was nobody more appropriate to end it than four guys who shed blood over there and have the biggest grudge."

Muller and his companions had been warned by the State Department, the Defense Department, the Defense Intelligence Agency and the National League of POW-MIA Families that they would be used for propaganda purposes.

Muller feels that they got as good as they gave--that pictures of him holding a deformed Vietnamese baby were offset by concessions offered by their hosts.

First of all, he said, Foreign Minister Nguyen Co Thach promised a "renewed effort" at a full accounting of the 400 MIAs, about whom nothing is known. It will be done through the VVA, not the administration.

Second, the government will admit U.S. doctors and scientists to Vietnam to make studies of victims of Agent Orange. American servicemen are haunted by the effects of Agent Orange, which the Veterans' Administration does not officially recognize as disabling.

The veterans were warmly received by the people of Hanoi and Ho Chi Minh City (formerly Saigon), Muller said.

"After all the stuff we dumped on them--20 millions tons of bombs and ordnance--I was stunned at how friendly they were. They have been indoctrinated on the difference between the administration and the people of this country. They are so deprived. It's a shame to surrender these people to the Russians," he said.

The government has also promised to receive other U.S. veterans who, Muller insisted, really want to go back--"just like the guys in World War II wanted to see the battlefields where they fought."

Muller said the mission was strictly "humanitarian--we're not diplomats or geopoliticians."

But the specter of what it could lead to--recognition of Vietnam--hung over the poignant expedition, and the State Department felt constrained to reiterate that "diplomatic relations are out of the question."

Sonny Montgomery regrets that as much as Bobby Muller.

"How are you going find out about the MIAs, how you gonna find out about the effects of Agent Orange, if we don't go in there? " he asked.

Supposedly, the Vietnamese occupation of Cambodia is the stumbling block. But the invaders threw out Pol Pot, murderer of about 2 million people, who nonetheless receives our tacit support in the United Nations.

The trip, however touching some found it, served to tell us once again that Vietnam retains its evil genius for creating rancor. Some Americans can never forgive the Vietnamese for the trauma of our defeat, which, of course, they blame on demonstrators and congressmen. They continue to regard the victorious leaders of a ravaged land as cunning fiends, not as the hungry, battered, desperate people who welcomed Bobby Muller and his fellow veterans.