The disintegration of Yasser Arafat's leadership of the Palestine Liberation Organization has been watched with cool detachment by Israeli officials, who view it as a delayed reaction to Israel's military defeat of the PLO in Lebanon last summer.

Despite fears in some quarters that the current turmoil will result in a takeover of the PLO by radical elements determined to wage a campaign of international terror, Israelis profess indifference. They have never accepted the description of Arafat as a "moderate," and they argue now that there is little difference between him and those seeking to overturn his leadership.

The only senior official to speak publicly on the subject, Foreign Minister Yitzhak Shamir, said in a television interview this week that what is bad for the PLO is automatically good for Israel, regardless of who emerges in control.

"I must say that it is good for Israel that there are domestic quarrels, breakups and divisions within the organization of the PLO," Shamir said. "This is one of the results of Operation Peace for Galilee Israel's official name for its invasion of Lebanon . It is the result of demoralization and disappointment in the wake of the tremendous defeat they had in Lebanon."

Shamir continued: "I am not afraid of radicalization of the entire organization. The differences within the PLO, to the extent that they are connected with political problems, are merely tactical. The differences are not fundamental. Arafat and his rivals have a common goal.

"Tactically speaking, it may be that Arafat's tactics are sometimes more dangerous for us."

Although in the official Israeli view there are no moderates or extremists in the PLO, only "terrorists," Arafat is generally credited even here with curbing indiscriminate acts of terrorism and with having raised the PLO's international standing, thus putting pressure on Israel to come to terms with the Palestinians.

"You will find Israelis who will argue that it is better if Arafat loses his position, so we know exactly who the PLO is," a Defense Ministry official said. A more clearly radical PLO, he said, would reduce the pressure on Israel to negotiate over the future of the occupied West Bank and Gaza Strip, which the government of Prime Minister Menachem Begin is committed to retaining.

Meanwhile, a Defense Ministry official said, there is a belief here that the intensity of the revolt against Arafat in northern and eastern Lebanon has reduced the number of attacks against Israeli soldiers in the south in the last week. Echoing Shamir, another official said, "They are busy among themselves, and that is good for us."

Israeli officials are determined to block any PLO return to southern Lebanon. Defense Minister Moshe Arens, speaking to the directors of the Jewish Agency yesterday, warned that "Israel will have no choice but to repeat its Peace for Galilee operation if the PLO comes back."

But a PLO move from Damascus and the Bekaa Valley to the northern Lebanese city of Tripoli, hinted at as a response to Syrian support for anti-Arafat forces, could provide the Israelis with one thing they are seeking.

To the Israelis, one of the most frustrating aspects of the Lebanon stalemate has been the lack of a target to strike back at when Israeli soldiers are killed in Lebanon. Before last summer's war, the PLO presence in southern Lebanon and Beirut provided such a target for the Israeli Air Force. But now soldiers of the multinational force patrol the streets of Beirut and a strike at the Syrians in eastern Lebanon runs the risk of setting off a general war.

Asked if a PLO military presence in Tripoli might not provide a target for retaliatory raids, a Defense Ministry official said no Syrian soldiers were in the area and added, "You have your answer."