In the dull-red brick auditorium building of San Jose High School, where the student body assembles and the PTA meets, a group of anticommunist Vietnamese refugees gathered recently to plot to retake Vietnam.

During four hours of songs, movies, dance acts and speeches, however, the meeting of the San Jose and other California chapters of the National United Front for the Liberation of Vietnam did not look that threatening, although the group is the largest of militant splinter groups of Vietnamese refugees seeking to overthrow the Vietnamese government.

Waiting to get in to the building, the group's U.S. leader, Pham Van Lieu, 56, a former colonel in the South Vietnamese army, denied published reports that his group has been using U.S. public parks for military training.

"First of all, we respect the laws of the United States. And next of all, we don't need to train here," he said. "We want to deny all military training."

However, continued Lieu, a man with gray hair and a broad, pleasant face, the group's members are "freedom fighters for Vietnam and the whole of Southeast Asia."

Even without military drill, he said, the Front's goal is "to liberate Vietnam from the yoke of Vietnamese communism, to expel the Russian imperialists from Vietnam and Indochina and to restore to Vietnam what we enjoy over here: freedom, justice and democracy."

Thirty young members of a newly formed Vietnamese Children's Club sat in three orderly rows on a concrete walkway outside the auditorium.

They were dressed alike in blue jeans and light blue shirts. Blue, elders explained, symbolizes youth and hope. Their scarves were yellow, the color of the nationalist flag.

The purpose of the club, elders said, is to ensure that the children do not forget Vietnam's language or traditions.

Most of the 500 adults were men, also dressed alike in tan pants and brown shirts.

"In our tradition, not many women take part in social political activity," interpreter Chuong Le said. Brown, it was explained, is the traditional color of the country people in Vietnam.

At the meeting, everyone sat quietly but applauded clamorously, Chuong Le said, at the announcement that "the use of the auditorium is free of charge." Efforts to interview audience members met with bashful giggles or insistence that the interpreter was the source of all knowledge.

In Lieu's keynote address, he listed the group's objectives: "to organize and improve the Front," to "raise the effort in the Vietnamese and American communities in support of the Front" and to "provide financial support for the Front." In the interpreter's account, Lieu did not mention taking over Vietnam.

Lieu admonished his listeners that in seeking support they should never use "threatening or rude language" but be "polite, patient and informative."

In one of the movies, soldiers wearing vines and camouflage outfits scampered up and down cliffs on ropes, tramped through jungles and sat around a campfire eating rice.

The star of the show was Hoang Co Minh, a former Vietnamese admiral who is chairman of the National United Front for the Liberation of Vietnam.

An American named Jim Barker spoke to the Vietnamese in their own language. Barker, who lives here, said he served in Vietnam a decade ago with the U.S. Army's intelligence division. "The Vietnam veteran has not surrendered the objective he presented his life to try to achieve," he said.

Barker insisted that "it won't take much to spark an overturning of the existing order" in Vietnam. "I would call it a mandate of heaven," he said.