On the eve of the Six Day War, the younger brother went looking for the older one. Benjamin Netanyahu was 18, an Israeli in a Philadelphia high school, taking his final exams. Jonathan Netanyahu, Yoni to friends and family, was 21, an Israeli paratrooper.

"I had this uncomfortable feeling that something would happen to Yoni," the younger brother recalls now. "I also felt I had to go back to Israel. I couldn't sit by and take my final exams."

Once in Israel, he wondered how he would find a young soldier preparing for war. In Jerusalem, people told him that there were paratroopers stationed in the orange groves near the town of Ramla. "I said, 'Do you know how many orange groves there are?' " But he went. He found the orange grove, he found the paratroopers, he found his brother, Yoni. "He couldn't believe I was there," Netanyahu says with delight in his voice. "Emotional moment," he adds quietly.

Something did happen to his brother. His left elbow was shattered on the Golan Heights as he tried to help a fellow soldier, only hours before the end of the Six Day War. Jonathan Netanyahu not only survived, he continued his military career. He passed a physical exam--his brother will tell you with a grin--when a doctor thought it was the soldier's knee, not his elbow, that was supposed to be examined for problems.

But these are the easier stories for Benjamin Netanyahu to tell about his brother. Entebbe is the hardest story, so he only tells part of it: When Benjamin Netanyahu, in Boston, heard on the radio in 1976 that the Israelis had raided Entebbe to free hostages on a hijacked plane, he assumed that Yoni would be leading it. So he called his other brother and asked, "Is Yoni back yet?"

Lt. Col. Jonathan Netanyahu, 30, who led the successful mission, was the only commando killed at Entebbe.

This weekend at the Four Seasons Hotel, the Jonathan Institute, which is named after Netanyahu's slain brother, will begin its second conference on International Terrorism. Netanyahu helped organize the private, Israeli-based institute whose public board includes people like Shimon Peres and Menachem Begin.

George Bush and the late Sen. Henry Jackson spoke at the institute's first conference on terrorism in 1979, on the third anniversary of Jonathan Netanyahu's death. "This was right after the Iranian revolution," Benjamin Netanyahu remembers, " . . . and we said Iran is yet to become a principal terrorist state."

But the main contribution of the conference, he says, was emphasizing "this is not an abstract problem . . . It's something being used by governments to attack the democratic world. And what unfortunately was said has become distressingly prophetic. This has become a cancer spreading throughout the world."

"I think of my brother very, very often," says Benjamin Netanyahu, 35. "We were very close. He was a model to so many people who met him that I never thought my view of him was subjective . . . Now a lot of us have ideals, but we tend to put our ideals in one compartment and our daily lives in another. Yoni was different. He couldn't live his life unless it was consistent with his ideals and principles."

Jonathan Netanyahu may be considered an Israeli hero, but his brother, Benjamin, hardly lives in his shadow. He is currently the deputy chief of mission at the Israeli Embassy, the number two position that he was tapped for by Moshe Arens (who is now defense minister) two years ago when Arens was ambassador here.

The path for his rising star has been unorthodox. A businessman, he had no previous diplomatic experience. "I'm not a diplomatic diplomat," he says, sitting in the lobby of the Four Seasons, waiting for a visiting Israeli diplomat. But he is a polished diplomat and a smart one.

"I was asked to come here by Moshe Arens from the private sector. He asked me, would you like to come and be my number two? I said immediately yes. I had spent with him 45 minutes in 1975 when I was a student at MIT . . . I wanted to talk to him about Israel's relationship in America. That was the end of it. I never heard from him. He never heard from me." Until seven years later when he was offered the post.

Part of his job is improving public relations between the U.S. and Israel, and he knows America well. He moved to Philadelphia in 1963 when his father, Benzion Netanyahu, a historian and an early Zionist in Palestine, accepted a position at Dropsie University. He later became chairman of the Jewish Studies Department at Cornell.

When Netanyahu returned to Israel to find his brother, he stayed to serve in the Army. Five years later, at 23, he started at MIT. "I thought, 'These 18-year-old whiz kids. I'm an old man. I have to catch up.' "

In the summer of 1973, his brother Yoni (who had gone to Harvard for one year before going back to Israel to be in the Army) came back to Harvard for summer school. The two brothers took a political science course together and went running together every day. Yoni, his brother says, planned to finish college as soon as he completed his Army obligations. He never did finish. Benjamin Netanyahu completed MIT with an undergraduate degree and a master's in business.

His wife, Fleur, is an English-born Jew whose family fled Germany in 1935 for South America and then England. They met in Boston when she was finishing Harvard Business School. "She's a management consultant by profession," he says, "but she says there's not a lot of time to engage in that when you're married to a diplomat."

They have been married two years. She is his second wife; he has a 6-year-old daughter from his marriage to an Israeli in his early twenties.

"After Yoni died, we were approached by a lot of people to try to establish all sorts of organizations and foundations and memorials in his name," Netanyahu says. "We didn't take an active part in them, because we didn't feel that Yoni needed a commemoration. His life and his deeds and the letters that he left behind were significant enough. They live on their own."

In fact, Netanyahu and his younger brother, Iddo, a physician, collected and edited Jonathan Netanyahu's letters in a book called "Self-Portrait of a Hero." Yoni Netanyahu was a prolific, passionate writer of letters that contained his thoughts on life and Israel. He wrote to his parents, brothers, friends, his wife--before what his brother calls "a painful divorce"--and then his girlfriend. And the recipients kept these letters.

When the organizers of the institute devoted to stopping terrorism approached Benjamin Netanyahu for his help, the family felt it was appropriate. "Yoni, after all, died in the war against terror," Netanyahu says. "He never viewed it as simply our own little battle. He viewed it as a battle of civilizations against barbarism . . . We thought this was something that touches his life, touches Israel's life, and touches the life of all free nations."

This year's conference speakers include Secretary of State George Shultz at the opening session Sunday night and U.N. Ambassador Jeane Kirkpatrick on terrorism and totalitarianism Monday morning; later, an academic panel will examine terrorism and the Islamic world. Tuesday morning, ABC's Ted Koppel will chair a panel of journalists speaking on terrorism and the media.

Of his own involvement in this year's conference, Netanyahu, who edited a book of the proceedings of the first conference, says, "I help to the extent that I can . . . in terms of my impressions of people who might be interested in this or people who might be contacted to speak."

Netanyahu attributes the problem of international terrorism to "the result of government-supported terrorism, and this is the problem we face today."

"If you take away state support there is virtually no international terrorism. You don't have the weapons, you don't have the embassies that are used as terrorist fortresses throughout Europe, you don't have safe houses, you don't have the intelligence." He believes international terrorism can be fought by democratic nations: "In order to curb international terrorism the democratic nations have to act in unison."

As for the much-publicized recent incidents of terrorism by Jews in Israel, he says, "It's obviously distressing, because it's something we don't want to see. But we have to look at it in perspective. It's a very, very small speck and in fact everyone agrees that what has been uncovered--that's it . . . We're opposed to terrorism within our borders and outside our borders, and if we discover the Jews are practicing terrorism then we act as a responsible country."

Ask him whether he sees his own political career continuing and he gives the standard diplomatic answer: "As long as I feel like I'm contributing, I'll stay. But," he adds, laughing, "I certainly don't have to stay in public life to make a living."