Senior diplomats here say the Soviet Union has begun joint military exercises with Syria, a move seen as escalating both the Syrian-Israeli missile crisis and the Kremlin's feud with Ronald Reagan.
The exercises, not yet offiicially confirmed here or in Syria, would represent a major Soviet policy departure on both of these fronts.
The Soviets have so far limited themselves largely to toughly worded public statements. This has been true even when the Soviet Union felt Washington was carrying its "anti-Sovietism" beyond words, with moves toward arms sales for China and Pakistan.
The reported military exercises, foreign analysts here say, would amount to a reminder that the Soviet Union has more than words at its disposal in countering Reagan administration policy.
At this writing, diplomats' details on the Soviet-Syrian exercises remained sketchy. But they were described as mainly "naval" and occuring against the background of increased Soviet naval strength in the Mediterranean since the outbreak of the Syrian-Israeli crisis in late April.
That crisis is of particular concern to the Reagan administration, which is striving for a delicate balance between traditional backing for Israel and strengthened ties with moderate Arab states, including key oil producers like Saudi Arabia.
Virtually all Arab states blame Israel for the dispute, which erupted when Israel downed two Syrian helicopters over Lebanon and Syria promptly stationed Soviet-made missiles in the area.
President Reagan has sent Philip C. Habib as a special envoy on two shuttle missions to the region in a bid to head off a war. US officials were quoted July 6 as saying Mr. Habib would soon be returning to the Mideast for further talks.
[Reuters reports that Syria claims to have shot down another pilotless Israeli reconnaissance drone over Lebanon July 7, but an Israeli military spokesman said the drone crashed due to a technical failure. Since the crisis began in April, Syria had downed seven other aircraft of this type.]
One senior diplomat here said the reported joint military exercises, without recent parallel in Soviet Mideast policy, "mean the Kremlin is raising the geopolitical ante" in the Syrian-Israeli crisis.
Questions of war and peace ultimately depend on the Syrians and Israelis, so the results of such a Soviet move were all but impossible to forecast.
Thus far, the Soviets have gone to great lengths to play down the chances of military involvement in the crisis, despite a formal 1980 friendship and cooperation treaty with the Syrians.
Apparently satisfied with the chance to snipe at the alleged "pro-Israeli" tilt of Us special envoy Habib, Moscow has all but avoided public refrence to the treaty with syria.
In an unusual move May 6, the Soviet newspaper Literaturnaya Gazeta went to the trouble of denying an Israeli radio suggestion that Moscow would "examine the question of increasing military aid to Syria," should the Israelis strike at the newly deployed Syrian missiles.
The Israelis had attributed such a statement to the Soviets' ambassador in Lebanon. Barely a week later, he stressed in Beirut that the Soviets wanted "peace in the area."
On May 16, the ambassador was quoted by Reuters as saying the missile crisis in Lebanon was "unrelated to the Soviet-Syrian treaty."
The same day, on Moscow television, the Soviets' chief foreign press spokesman repeated what has become traditional political backing for the Syrians in the crisis, but added that a resolution should be found through "patient talk."
The official Soviet news agency, Tass, meanwhile, denied Israeli charges that Soviet advisers were stationed alongside Syrian troops in Lebanon.
Soviet President Leonid Brezhnev warned in a speech in the Soviet republic of Georgia that "one hasty step" in Lebanon could ignite "flames of war" that might "engulf the whole of the Middle East." But he did not mention Syria or the Soviet-Syrian treaty in his address.