Syria is willing to pull its Army out of Lebanon if the price is right. Diplomats and Western intelligence sources believe Syria's price is a security guarantee for its lengthy western border and a complete and simultaneous Israeli withdrawal. At the moment, the Syrians are sitting contentedly on the sidelines watching the American-sponsored talks between Lebanon and Israel.
''Washington and (US Middle East envoy Philip C.) Habib have not yet produced anything Syria can get its teeth into. . . . The shape of the (Lebanese-Israeli) agreement now is totally unacceptable,'' said a senior Western diplomat.
Syria wants to make sure Lebanon remains Arab, which means the border between Lebanon and Israel must be closed, the diplomat said. That would rule out Israeli military patrols in southern Lebanon as well as trade and tourism. Israel currently is demanding those as part of any agreement with Lebanon.
A Lebanon free of Israelis would minimize the security risks posed to Syria along its western border, Syria believes. Diplomats said Syria thinks that would push Israeli troops out of artillery range of Damascus. It would also cut down on dissidents and anti-Syrian groups using Lebanon as a staging ground for political or terrorist acts against President Hafez al-Assad's regime.
With this goal in mind, Syria might even be willing to accept American or international troops patrolling south Lebanon instead of the Israelis, a diplomat suggested.
The Syrians are banking on their influence in Lebanon returning to its pre- 1975 level which was before Syrian troops entered the country to quell the Lebanese civil war. That would mean Syria would carry considerable weight while Israel would have very little sway, diplomats said.
The diplomats and intelligence sources, who are in regular contact with the government, noted that Assad spelled out a very clear, rational argument in a speech delivered to the nonaligned conference in New Delhi.
Referring to the Israeli demand that the Lebanese Army be restricted in size and weaponry in southern Lebanon, Assad said this ''means, in other words, that the state or other states neighboring Israel are not free to deploy their forces freely within their own internationally recognized borders.''
Noting that Israel is also requesting land and air patrols, Assad asked, ''What will remain of independence and sovereignty of any country?
''What sense of independence shall we Arabs be left with if Israel is to have its way and its notions about peace and security are materialized? Shall we call them Israel's peace requisites or rather its capitulation terms?''
Diplomats say this appears to be Syria's bottom line on the Lebanon peace talks. But they add that until the talks begin to include Syria, it is difficult to tell exactly what Syria's position will be.
''Syria's limits of tolerance are unknown. . . . When the talks start, a lot could be finessed,'' said a diplomat, pointing out that some obstacles could be cleared by simply not writing down some conditions that would be intolerable if publicly admitted.
However, one thought is bound to stick in Syria's mind during the negotiations, diplomats agreed. And that is that the Lebanese settlement could set a precedent for a settlement on the Israeli-occupied Syrian Golan Heights.
When Mr. Habib has a deal between Lebanon and Israel, it will be time to open a second negotiating process with Syria, diplomats said. However, fighting could erupt between Syria and Israel before then.
''We're back into the fighting season again,'' remarked one diplomat. Lebanon's Bekaa Valley, where about 30,000 Syrian troops confront the Israelis, is beginning to dry up from a torrent of unusually heavy winter rain. Military sources say it is only a matter of weeks before the ground is hard enough for warfare.
Some diplomats suggested that battle could be used by either side to push the negotiations their way or freeze them. Although the military sources said there is no sign yet of a buildup by either side, none would be surprised to see at least minor skirmishes.
Diplomats say there are a few practical reasons why Syria would not want a war, including that moral is low and Syrian troops remain undertrained.