Lausanne, Switzerland — Lebanon's reconciliation talks opened Monday with a reminder of how important Syria will be to its outcome - and how great are the barriers to success. The American presence, important if discreet at the first round of talks last year, seemed limited this time to an attache from the American Embassy in Beirut.
Members of virtually all of Lebanon's warring communities conveyed pessimism before the talks began. Opening them, the country's Maronite Christian President , Amin Gemayel, made a brief keynote speech. His two main rivals, Lebanon's Syrian-backed Druze and Shiite Muslim militia chiefs, would not even meet his gaze.
At the entrance to the conference room stood a metal detector to dissuade the chieftains from talking with guns on their laps. Their forces have been murdering each other since 1975.
Still, the fact that the conference has started signals that Damascus intends to try to impose a Pax Syriana among the Lebanese - having in effect defeated President Reagan's bid for a Pax Americana. And true to form, Syria seems intent on avoiding outright or irrevocable support for any of the Lebanese rivals. Damascus seeks instead a delicate balance in which it would hold the central mediatory role.
The Syrians supported Mr. Gemayel's militia foes in all but destroying his Lebanese Army and political position last month. Thoroughly humbled, Gemayel then bowed to Syria's longtime demand for scrapping an American-mediated peace accord signed after Israel's 1982 invasion of Lebanon.
But now that Gemayel has been so weakened, Damascus is offering him both a carrot and a stick as the talks resume.
The carrot, Lebanese analysts say, is the possibility of a political compromise there that would blunt at least a few of the most extreme demands of Gemayel's Druze and Shiite foes. The stick: Go along with that compromise, which would nonetheless guarantee widened Lebanese Muslim and Syrian influence, or face the possibility of yet another round of fighting against the superior, Syrian-backed opposition forces.
Appropriately, the conference had not even opened before the crucial role of its Syrian ''observer'' - Vice-President Abdel Halim Khaddam - was made inescapably, and publicly, clear. Because of a delay in his arrival, the conference got under way seven confused hours later than originally planned. Even then, Mr. Khaddam had not actually arrived at the conference site.
But Gemayel's opening words were an assurance the Syrian visitor had apologetically told him he would be in a bit later.
''Khaddam doesn't need to be here to make Syria's presence felt,'' a veteran Lebanese analyst remarked as the conference began.
''Look how the Syrians' influence has already, at least for now, silenced some of the most anti-Gemayel points in the opposition's stand.''
One example cited was the fact that Druze leader Walid Jumblatt had dropped earlier demands that Gemayel resign before any compromise could be discussed, much less sealed.
But a joint political proposal drawn up by the Druze and Shiite opposition did include other demands that Gemayel may find hard to accept. And even if Gemayel were to lean toward compromise, it remains uncertain whether he can bring along more extreme, anti-Syrian elements in Lebanon's Maronite Christian community.
The assumption here is that at least some of the opposition demands will soften if the conference goes anywhere at all. Indeed, the wording of parts of the opposition platform, leaked to reporters, seems purposefully vague, as if to allow room for movement.
But an immediate compromise, on all sides, seemed unlikely. A spokesman for right-wing former President Camille Chamoun said that just as the parley got under way, word came of ''huge-scale shelling'' of the Christian east Beirut.
Arab analysts here said this might be a reminder - with the tacit Syrian OK that Lebanese politics makes necessary - of the opposition's ability to push Gemayel and the Christians even further militarily.
But Syria's preference, most analysts maintained, would be to engineer and dominate a workable political compromise.
Lebanon, meanwhile, had come to the Swiss lakeside in all senses. The conference site, the stately Beau Rivage Hotel near the shore of Lake Geneva, wore a face distinctly different from that which has for decades greeted Europe's trendiest tourists and most exalted society figures.
Barbed wire ringed its grounds. A sandbagged checkpoint stood at the entryway to its driveway.