In the continuing make-or-break efforts to resolve the impasse over the Palestinians trapped by the Israelis in west Beirut, three tendencies are asserting themselves.
* The edging of the negotiations toward a broader Middle East framework than just Lebanon and the Palestinians.
United States special envoy Philip C. Habib left Beirut over the weekend for visits to Syria, Saudi Arabia, and Egypt. He headed for London July 25 to confer with King Hussein of Jordan after having failed in Cairo to persuade Hosni Mubarak to accept any of the Palestinian guerrillas.
* The Palestine Liberation Organization (PLO) and Syria, both militarily mauled in the first week of the Israeli thrust into Lebanon, are proving remarkably resilient in their risky brinkmanship to turn the stalled seven-week-old Israeli invasion to their advantage. (Elaine Carey reports from Beirut on the PLO's persisting military strength against Israel's modern Army, Page 9)
When the Israelis sent their air force over Lebanon's Bekaa Valley July 24 to take out some new Soviet-supplied SAM-8 missiles installed there, the Syrians shot down an Israeli Phantom fighter. This was the first time Israel has conceded the downing of an Israeli plane by Syrians since this fifth Arab-Israel war began. The PLO, meanwhile, has been mounting successful ambushes of Israelis closer to Beirut.
* Israel is finding itself increasingly frustrated - after its initial military successes - by the restraints on further military action represented by: international (and particularly US) pressure; the likely cost to Israel in human lives and material of a renewed all-out offensive; and the souring of that segment of Lebanese opinion originally favorable to it.
Reports that Israeli Foreign Minister Yitzhak Shamir will visit Washington this coming week to confer with the new US Secretary of State, George Shultz, reflect Israeli frustration. (So too, does Israel's July 25 air bombing of west Beirut for the fourth day running.)
Parallel reports that Egyptian Foreign Minister Kamal Hassan Ali is also contemplating a visit to Washington suggest that the Egyptians intend to keep up the pressure on the US for a continued active American role sooner rather than later in a broad Middle East settlement.
Given the potentially explosive situation of the Israeli siege of west Beirut , the immediate need is to find a way to get the 6,000 PLO guerrillas trapped there out of the city. The problem is both how and where to relocate them. Mr. Habib reportedly pressed the Arab governments visited by him over the weekend to cooperate in finding a solution.
In this, the role of Syria is crucial. Geography makes Syria the easiest place to move the PLO to, even if only as an initial staging post. Under safe-conduct, the PLO could proceed overland across the Bekaa Valley into Syria or by sea to the Lebanese port of Tripoli or the Syrian port of Latakia north of Beirut. But Syrian President Hafez Assad says no.
As then Secretary of State Henry Kissinger discovered during his shuttle diplomacy of the mid-1970s, Mr. Assad is a cool and skillful negotiator - some would say ''gambler'' - in extracting advantage for Syria in situations that to others seem hopeless.
Many observers believe his cooperation in evacuating the PLO from west Beirut can still be obtained - but on his terms. These, it is surmised, include: a guaranteed central role from now on for Syria in any negotiations on a settlement, whether limited to Lebanon or extended to the Arab-Israel conflict as a whole; a promise from the US that Washington will help in the process of getting Israel to ''de-annex'' the Golan Heights, seized from Syria by Israel in the 1967 Arab-Israel war and brought under Israeli law last December; and perhaps financial compensation from such oil-rich Gulf Arab states as Saudi Arabia for the burden of being in the front line against Israel.
The PLO's prime condition for its cooperation with Habib in any withdrawal plan from west Beirut is US recognition and willingness to deal directly with it.
The US till now has stuck by its insistence that direct dealings and recognition can come only if the PLO first unequivocally accepts Israel's right to exist. The PLO is apparently moving in this direction, but in a manner still too equivocal for Washington.
The PLO also wants a clear US commitment to the ''full autonomy'' promised the Palestinians on the West Bank and in Gaza in the ''framework for peace'' agreed to by Israel, Egypt, and the US at Camp David Sept. 17, 1978. The Palestinians do not want to be fobbed off with the Israeli preference for a Palestinian homeland in Jordan, rather than alongside Israel west of the Jordan River.
That ''framework for peace'' specifically envisaged Jordanian participation in the autonomy talks - which might explain Habib's unexpected flight to London to confer with King Hussein.