"The United States must give up backing the military government of South Vietnam," Everett I. Mendelsohn, associate professor of History of Science, said yesterday on his return from a fourweek tour of the area.

The recent Viet Cong attacks had trapped Mendelsohn in Saigon for the last ten days. Although "never in personal danger" while there, Mendelsohn said that he did "hear gunfire at all times of the day and woke up two or three times a night to the sound of explosions."

He was in Vietnam as part of a planned three-week tour of Southeast Asia by the American Friends Service Committee. At his Boston press conference yesterday, Mendelsohn said that he went there "to investigate the possibilities for political change."

Mendelsohn said that he believes "the United States should take immediate steps to change the Vietnam war from a military to a political conflict."

"The current government of South Vietnam is dishonest, filled with corruption, and has little respect from the people of South Vietnam," he charged, proposing immediate new elections.

"Peace talks could take place right now if a civilian government were in power in South Vietnam," he said. "The Saigon government has no appeal and continues to exist only because of United States military support."

After talking with representatives of the National Liberation Front, Mendelsohn said that they "see the gradual phasing of U.S. troops out of Vietnam as the most logical solution to the war." He advocates U.S. recognition of the Front.