Syria's foreign minister has arrived for talks in Moscow at a time when the Kremlin is bidding to protect old alliances and secure new ones in an unstable Mideast.
Syria, which signed a friendship pact with Moscow in late 1980, is a key element in Soviet strategy.
But ultimately, the degree of Soviet success will likely depend on the overall situation in the Arab world, and on US policy in the strategically important region.
Some Arab sources here said the Syrian envoy, Abdul Halim Khaddam, was in Moscow to seal agreement on widened Soviet military backing. At this writing, Soviet and Syrian officials had not confirmed this.
But diplomats here said there could be little doubt of Soviet desire to consolidate ties with Syria. The Khaddam visit follows Israel's effective annexation last month of the Syrian Golan Heights, captured in the 1967 Mideast war. It coincides with a UN Security Council debate on the issue that has placed Washington in an embarrassing position. Despite pressure from even moderate Arabs for a resolution including sanctions against Israel, the United States is pledged to veto any such move.
Thus Soviet officials seem to feel the time is particularly ripe for a start at recouping lost influence in the Arab-Israeli arena.
The Soviets' ''best scenario,'' judging from both private and public comments here, would include:
* The final demise of US-sponsored talks on Palestinian autonomy that grew from the 1978 Camp David peace accords.
* A gradual dilution of Egypt's strong pro-American position by the late President Sadat's successor, Hosni Mubarak, particularly after Israel gives him back the rest of the Sinai in April.
* Increasing impatience with Washington among moderate Arab states, like Jordan, over an American failure to come up with an acceptable resolution of the Palestinian issue.
* A temptation among firmer US allies like Israel and Saudi Arabia, each for its own reasons, to be nicer to Moscow as a signal of displeasure with Washington.
* Strengthened ties with Syria, until recently something of an outcast in the Arab world but moving back into the mainstream after Israel's Golan move and the failure of Saudi Arabia to secure full Arab support for its Mideast peace plan.
At least some items on this checklist could indeed occur, Arab and Western analysts here suggest. But they point to potential problems as well.
For one thing, it can be presumed that the Americans will be doing their utmost to produce at least the illusion of movement on the Palestinian autonomy front. Secretary of State Alexander M. Haig Jr., in hopes of reviving momentum in the autonomy talks, was in the Mideast Jan. 14 as the Syrian foreign minister flew to Moscow.
Also, the Soviet alternative of a new international peace conference strikes veteran Mideast analysts as no more promising than the unencouraging prospects for Palestinian autonomy talks.
Even in relations with treaty-partner Syria, the Soviets could conceivably run into trouble. Before signing on with Moscow in 1980, Syria steadfastly, and acrobatically, avoided commitment to either superpower camp.
Syria signed with the Soviets from a position of weakness, isolated regionally as longtime rival Iraq moved toward the Saudis and other oil neighbors after Mr. Sadat's peace with Israel. The prospect of reclaiming the occupied Golan, either with words or arms, seemed more unlikely than ever. Muslim fundamentalists spearheaded violent unrest at home.
Some Arab analysts here suspect that Syria, which still has problems but is visibly less isolated regionally, may gradually de-emphasize its closeness to Moscow or at least become a less reliable Soviet ally.
The Soviets clearly hope this will not happen. They have loudly decried the Israeli decision on the Golan, and loudly denounced the declared US intention to veto any UN call for sanctions over the issue.
And they have invited Mr. Khaddam to Moscow for ''consultations in accordance with'' the 1980 friendship pact.
One early indication of the future course of Soviet-Syrian ties could come on the ground. Diplomatic sources here reported in December (before Israel's Golan move) apparent preparations for joint Syrian-Soviet military maneuvers. A Syrian source here said he could neither confirm nor deny the report, which said Libyan units might also participate.