Middle East : PLO’s Loss in Lebanon Sets Power Brokers Scrambling : Neighboring nations and the United States seemed unprepared for the sudden defeat. Looming next is a confrontation with Israel.

The power of the Palestine Liberation Organization in southern Lebanon shattered so suddenly and completely over the last 10 days that the political brokers of Lebanese affairs were still scrambling for position at week’s end.

Syrians, Israelis, Americans and the resurgent central government in Beirut appeared unprepared for the calamitous defeat of 6,000 PLO guerrillas at the hands of the Lebanese army. Military realities outraced political compromises.

Yasser Arafat’s PLO headquarters in Tunis could find no negotiating foothold as its guerrillas were overwhelmed at the southern ports of Sidon and Tyre. For the third time in a decade, his Fatah fighters were outgunned in Lebanon. In 1982, they held out 10 weeks against the Israelis in Beirut. The next year, Syria and its supporters drove them from the northern port of Tripoli.

This month came the turn of Fatahland, the PLO stronghold in southern Lebanon and Arafat’s last redoubt within striking range of Israel.

Pushing south from Beirut last week, the reconstituted Lebanese army battered PLO forces in the hills above the big Miye ou Miye and Ein el Hilwa refugee camps in Sidon. After four days, with more than 40 dead, the 5,000 Palestinians gave up the fight against superior Lebanese armor and numbers. The guerrillas retreated to the camps and began turning over their heavy weapons, a condition of the cease-fire.

At Tyre this week, 1,000 guerrillas surrendered their heavy arms without a shot after Lebanese soldiers surrounded three refugee camps.

The sudden collapse of Palestinian power hastens President Elias Hrawi’s program to re-establish Beirut’s control over the country. Two weeks ago, the question was whether the army should risk a fight with the PLO. Now, before the politicians were ready for it, a confrontation looms with Israel.

If the army intends to secure the south, the next likely target is Jezzine, a Christian town 12 miles east of Sidon, controlled by the South Lebanon Army, a 2,600-member Lebanese militia trained and bankrolled by the Israelis. It symbolizes the potential for conflict as Beirut tries to put its country back together.

Here’s a rundown on how the mix of interests hang in the balance:

Israel

Security is Israel’s main concern. Lebanon, on its northern border, long has been a problem. Jerusalem is best served by a supportive regime in Beirut, which is why the Maronite Christians were courted, or by keeping power so fractured that no element can pose problems. The South Lebanon Army is Israel’s contribution to fractured power.

Last week, as the Lebanese army rolled up the PLO forces outside Sidon, Israeli Defense Minister Moshe Arens assayed the army’s possible move against Jezzine and the threat that would pose to the security strip protecting northern Israel. He told a reporter: “We have not given our agreement, and we will not give it. We paid a very heavy price to secure peace and security for the residents of northern Israel.”

Nor is Israel willing to let Syria, prime sponsor of Hrawi’s government, gain strategic advantage through Beirut’s expanded control in the south. Jerusalem has advised Damascus privately that its 40,000 troops in Lebanon cannot cross specified “red lines” without provoking an armed response, diplomats confirm.

Syria

While it was a much-hailed member of the U.S.-led coalition against Iraq, President Hafez Assad’s government knocked out Maj. Gen. Michel Aoun, its Lebanese Christian nemesis, and signed a cozy treaty with the Hrawi regime giving Damascus virtual veto over Beirut’s foreign policy. More than before, Syria calls the shots in Lebanon, and Gen. Emile Lahoud, the army commander, would not have moved against the PLO without Syria’s consent.

A PLO loss suits Syrian interests, as Assad and Arafat are old antagonists. Assad keeps the Palestinians in his territory under tight control and wants Hrawi to do the same.

United States

Washington has supported the army’s extension of central power and diplomatically backed the 1989 Taif Accords, which authorized the process. Ambassador Ryan Crocker was in close contact with the Hrawi regime as the military effort by the U.S.-trained army was planned.

U.S. policy on Lebanon has generally lined up with Syria’s despite differences between the two countries otherwise. This confluence of interests has caused Washington problems in Israel. Unconfirmed reports in the Middle East say U.S. diplomats hope to avoid further friction by proposing that Hrawi compromise on Jezzine, declaring Beirut’s control but stopping short of sending in the army in strength.

Lebanon

The army that put down the PLO at Sidon and Tyre epitomizes a fresh wind sweeping the battered little country. Many officers are Christians who stood with Aoun to the end. Now they are fighting alongside Muslims and Druzes under the Lebanese flag. There is “a unity, a real chest-thumping pride,” said a longtime Beiruti. And there is no shortage of combat experience.

What happens now to the Palestinians is unclear. But they have been hurt by Hrawi’s campaign for a Lebanon for Lebanese. The refugees will remain, but the 6,000 guerrillas could be forced out of the country again. A compromise might send them to the Syrian-controlled Bekaa Valley, the equivalent of deportation. But Minister of State Abdullah Amin, who has been negotiating with the PLO, said Thursday they would not be deported.

The Palestinians in Lebanon

Here is a brief chronology of the Palestinian presence in Lebanon: 1948-49: Thousands of Palestinians flee when Israel is formed, enter Lebanon. 1970: Palestine Liberation Organization establishes its main bases in Lebanon after being forced from Jordan; PLO builds virtual state-within-a-state. Aug. 12, 1976: Hundreds of Palestinians massacred by Maronite Falangists in Tel al Zataar refugee camp in Beirut. March 15, 1978: 30,000 Israeli troops invade south Lebanon in abortive bid to crush PLO. June 6, 1982: Israeli army invades Lebanon again and seizes Beirut, besieging PLO forces. In August, Yasser Arafat and thousands of PLO fighters begin to evacuate Beirut. Sept. 22, 1982: Maronite militia slaughters hundreds of unarmed Palestinians in Beirut camps. September, 1983: Syrian-backed radical Palestinian factions mutiny against Arafat in Tripoli and force him from his last stronghold in Lebanon. May 20, 1985: Syrian-backed Shiite Muslims besiege Palestinian camps in Beirut to prevent PLO comeback. July 8, 1988: PLO quits Beirut camps and retreats to Sidon. July, 1991: Lebanese army moves into south, clashes with PLO.

Lebanon at a Glance Population: 3.3 million Area: 4,036 square miles Languages: Arabic, French, Kurdish and Armenian Religions: Islam (Sunni, Shiite and Druze, an offshoot sect), Christianity and Judaism Currency: Lebanese pound Economic activity: Trade, food products, textiles, cement, oil products, agriculture (fruits, olives, tobacco, grapes, vegetables, grains).

The Key Players Ryan Crocker, U.S. envoy Elias Hrawi, President of Lebanon Moshe Arens, Israeli defense minister Hafez Assad, President of Syria