Two Vietnam veterans, using a defused grenade to show how booby traps killed men they called their "buddies," testified today about the dangers of the communist home-militia forces that retired Army general William C. Westmoreland has said were "civilians" and should not be counted as enemy troops.

However, the effect of their graphic testimony for CBS seemed diluted later in the day when the jury in Westmoreland's $120 million libel action against the network and three men learned about a CBS executive's criticism of Westmoreland and CBS codefendant George Crile.

Reading from a transcript of an interview only recently allowed into the case, Westmoreland lawyer Dan M. Burt quoted CBS Executive Vice President Howard Stringer as saying Westmoreland "should have been fired years ago."

The comment, which Stringer apparently believed had been off the record, was made after the 1982 documentary at issue in the case.

Stringer also was quoted as saying of the broadcast, titled "The Uncounted Enemy: A Vietnam Deception," that he "didn't vet [examine] enough." He also is quoted as telling author Don Kowet: "George [Crile] is a conspiracy thinker," although in subsequent pretrial testimony, he denied having said that.

Earlier in the day, Army veterans H. Daniel Embree and Daniel Friedman were asked to comment on Westmoreland's testimony that "we were not fighting" home-militia troops, which the general described as mainly "defensive."

"Those people were fighting us, and we were trying to fight them," said Embree, a West Point graduate sent to Vietnam in 1966 as a first lieutenant.

Friedman, who arrived there in November 1967 as a private first class with the 17th Armored Cavalry, said mines and booby traps laid by persons that U.S. troops often considered friendly were "our primary cause of concern . . . ."

"I saw too many of my buddies go down because of them not to be concerned by them," said Friedman, who received two Purple Hearts and counsels veterans for New York State.

Their appearance marked one of the few times during the four-month trial that testimony focused on actual combat rather than on technical debate among intelligence officials about enemy strength.

As Friedman testified about Vietnamese villagers who waved one moment and fired the next, and Embree rigged a mock booby trap across the front of the witness stand, the realities of the ground war that ended almost 10 years ago for the United States were recreated graphically.

In a conversation out of the jury's hearing, Westmoreland attorney David M. Dorsen protested that "to have a witness just talk at some length as to buddies of his that were injured by mines and booby traps is inflammatory and essentially irrelevant and distorts the war, much less the case."

U.S. District Court Judge Pierre N. Leval told the lawyers that he would "inept" during his CBS interview. "Yes," Crile responded, "he seems stupid."