Secretary of State George Shultz has the delicate mission of trying to salvage some portion of the US Mideast policy at a time when the entire policy seems in imminent danger of splitting apart.
In a region where appearances count for a lot, the United States appears woefully on the defensive, its Reagan peace initiative blocked by the inability of key actor Jordan to join peace talks, and its bombed Beirut embassy lying in tragic ruins.
The Shultz visit itself, coming at a time when the Lebanon situation is murky rather than, as had earlier been hoped, when the essential elements of an Israel-Lebanon agreement were already in place, has elements of the desperate as well as of the determined.
The secretary's itinerary is open-ended after his initial three days in Cairo , followed by meetings in Israel beginning on Wednesday. During the trip, he will have to confront:
* A deadlock in Israel-Lebanon negotiations on terms for a withdrawal of Israeli troops from Lebanon - Mr. Shultz's top priority - after the talks appeared to be on the verge of success.
* Clear signals from Syria, which has the power to veto any Israeli-Lebanese agreement by refusing to withdraw its troops from Lebanon - that its wishes cannot be ignored.
* A cold reception from some moderate Arab leaders to President Reagan's hint - in an effort to revive his peace plan - that the US and moderate Arab states should move forward regardless of opposition from the Palestine Liberation Organization.
Mr. Shultz's first priority is to try to rescue the Lebanon talks.
The deadlock in the Lebanon negotiations comes as a bitter setback. Both Israeli and US officials had believed only 10 days ago that major obstacles had been significantly softened if not yet fully overcome. Then came the explosion at the US Embassy in Beirut.
Although the perpetrators have not yet been definitively identified, Israeli sources believe them to be Syrian-inspired in an effort to warn Lebanon's government that not even the US can protect President Amin Gemayel's regime if he signs a pact that is not to Syria's liking.
As Mr. Shultz was preparing to leave Washington, President Gemayel vowed on Lebanese news media not to sign any agreement allowing any Israeli military forces to remain in Lebanon. He also rejected Israel's firm demand that Israeli-backed southern Lebanese militia leader Maj. Saad Haddad be reintegrated into the Lebanese Army and put in charge of security in southern Lebanon.
This effectively negated understandings the Israelis thought they had with Lebanese negotiators on joint Israeli-Lebanese patrols in south Lebanon and on at least some major role for Major Haddad, although his final position was still in dispute.
Thus Mr. Shultz will be faced with the tricky task of reassuring Lebanon while finding a formula that satisfies Israel about the security of its northern border.
There is pressure from several ministers in the Israeli Cabinet for Israel to cease negotiations and to withdraw unilaterally to about 45 kilometers from Israel's border and remain there until Lebanon changes its positions. But Prime Minister Menachem Begin has postponed full debate on this question until after Mr. Shultz's visit.
However, in the process of reassuring the Lebanese, Mr. Shultz will be confronted head-on with Syria, the unseen negotiating partner.
The increasing volume of war talk coming out of Syria - insisting Israel is about to attack - is seen by many Western and Israeli analysts as a dangerous means of raising tensions to remind both countries that Syria will not accept an agreement that does not suit its interests. And Syria has made it clear that it will not accept a role for Major Haddad - whom it sees as an Israeli surrogate - or any residual Israeli troop presence in Lebanon.
At the moment Syria seems to have little incentive to ease Mr. Shultz's path. While the US has signaled Syria - via a message from President Reagan - that it considers the Israeli-occupied Golan Heights to be negotiable territory, Israeli Prime Minister Begin quickly responded that Israel will never give back the Heights, which it won from Syria in the 1967 Arab-Israeli war.
Mr. Shultz has no scheduled stop in Syria - although the possibility has been discussed - and special US negotiator Philip C. Habib has not been in Damascus this year.
To complicate matters further, behind Syria there stands its newly active ally, the Soviet Union, which has backed the Syrians with increasing amounts of arms and rhetoric. Many observers say the Soviet Union will want some acknowledged role in the Mideast peace process - something the US has tried assiduously to avoid - before it encourages its increasingly dependent Syrian ally to facilitate a US success in Lebanon.
The Syrian-Soviet specter also haunts any attempt to revive the Reagan peace initiative. This plan - which called for solution of the Palestinian problem by creating a Palestinian entity linked with Jordan on what now is the Israeli-occupied West Bank - was thwarted earlier this month when the PLO vetoed participation of Jordan's King Hussein.
Mr. Reagan suggested on Friday that the PLO should not be allowed to impede efforts to settle the conflict. But getting the Arabs to rescind the mandate they gave the PLO in l974 as sole spokesman for the Palestinians is seen by experts here as highly unlikely. Egypt's President Hosni Mubarak, a supporter of the Reagan plan, has already responded that the PLO is still the Palestinians' sole representative.
US officials remain hopeful that some formula may yet be found that will encourage King Hussein to change his mind. Progress in Lebanon would be an important step, since it would give US credibility as a mediator a big boost.
But Syria, which opposes the Reagan plan because it provides no role for it or its PLO ally, can veto progress in Lebanon if it believes this will revive the Reagan plan. So can Israel, which opposes the Reagan plan's call for return of West Bank territory in return for peace.