The United Jewish Appeal has launched trips to Israel and Lebanon in an effort to counter what its officials consider "distortions" in the media about Israeli military operations.

More than 100 American Jewish community leaders took part last week in the first tour, which from the Israeli vantage point appears to have been a striking success.

"When we began, I wouldn't be surprised if about 30 percent of the group had misgivings about the war ," said Washington lawyer Gerald Charnoff, a participant. "But based on the commitments they made at the end, there was a strong shift, a recognition that there was considerable justification for this war. It's bloody and costly, but it had to be, sooner or later."

The three-day visit included a stop at a military hospital near Tel Aviv, inspections of mountainside Palestine Liberation Organization ammunition depots and battle-scarred Lebanese towns, interviews with Israeli soldiers and Lebanese refugees, and talks with Israeli officials, including Prime Minister Menachem Begin.

Officials of UJA, a charitable organization, declined to provide a list of those who attended. But interviews with individuals whose names they did supply produced a number of outspoken impressions about the "state within a state" that the Palestine Liberation Organization had forcibly carved out for itself in southern Lebanon.

"I think everybody is sorry about the civilian casualties," said Elton Kerness, executive vice president of the UJA Federation of Washington, "but we were told by people we met that the PLO uses civilians as shields. . . . In the hospital, I talked to a paraplegic Israeli boy who said he and his buddies got hurt because they hesitated when they saw the PLO come out using boys as shields."

The Israeli government provided military liaison officers and guides for the UJA group. "Obviously the thing was prepared for," said Morton Kornreich, a New York insurance broker. "But we weren't propagandized. We saw what we wanted to see."

Elaine Winik, president of the Greater New York United Jewish Appeal, said this was her 44th trip to Israel since 1950 but on this one, "I went a little scared. . . . I remember Golda Meir saying once that we can forgive them for killing our kids, but we can't forgive them for making us kill theirs. . . . I was thinking, 'How can I defend this?' "

She said her doubts began to dissolve when she got to the military hospital and saw two small Lebanese children who had stepped on a Syrian mine. Then she noticed a man and a woman, both Arab, standing by their side.

"I asked who they were and a doctor told me, 'The Israeli army flew them down. You don't think sick children should be without their parents, do you?' "

Charnoff said he was struck by the steady flow of Lebanese refugees moving south into Israeli-held territory, many going back to homes the Palestinians had forced them to leave.

"There were hundreds a day--cars and trucks with mattresses and suitcases piled high," he said. "My conception is that one doesn't go into occupied territory if one is afraid of the occupier."

He said the devastation was much less extensive than he'd imagined, confined in Sidon, for example, to "probably four to six square blocks." By contrast, in Damour, just south of Beirut where the PLO had killed and driven out thousands of Christians a few years ago, "I'm not sure there was a house without a shell in it."

Charnoff said he understood "there was heavy artillery shelling" of Damour before the PLO fled and the Israelis moved in, but "other people tell me that the most damage was probably due to the fighting between the Christians and the PLO in 1975 to 1977."

William Brinton, a San Francisco lawyer and the only non-Jew on the three-day visit, said it was "perfectly obvious to me that the PLO was operating a state within a state and had imposed its will on Lebanese nationals through murder, extortion and intimidation."

The American contingent was also struck by two big tunnels they saw that the PLO had dug into hard mountain rock to store munitions and weapons, from attack rifles to Katyusha rockets. "You didn't need to crouch to go into them," Charnoff said. "They had openings like the entrance to the Baltimore-Washington tunnel."

At bottom, Charnoff suggested, the question is, 'Can organized society fight a war with guerrillas mixed in with civilians?' That is a troublesome question, but I don't think you admit you can't beat terrorists hiding in a civilian population."

UJA executive vice president Irving Bernstein said the the 110 people on the first trip included leaders from the 22 biggest Jewish communities in the country. Another delegation, from 30 "intermediate" cities, will leave today, he said.

"We do this trip annually as part of our UJA campaign process," Bernstein said. "But this time we went into Lebanon because of what we felt was distortion in the media of this country."

Those invited, he added, were "not the wealthiest or the most influential" in the American Jewish community, but rather were "people who would know a story and be able to articulate it."