The Kremlin has dispatched a military envoy to Syria and toughened its public stand on the Middle East war. But it appears reluctant to encourage a widening of that conflict.
A government statement issued late June 14, the toughest to date, said: ''The Soviet Union takes the Arab's side (in the conflict) not only in words, but in deed. . . . The present-day Israeli policymakers should not forget that the Middle East is an area lying in close proximity to the southern borders of the Soviet Union, and that developments there cannot help but affect the interests of the USSR. We warn Israel about this.''
The statement did not say what practical steps the Kremlin might be contemplating.
Like earlier Soviet declarations, it made no mention of Syria, stopped short of pledging military support for Israel's battlefield foes, and said peace should be established via unanimous United Nations Security Council decisions.
Senior officials could not be reached for comment, though one lower-ranking Soviet analyst said privately he felt his country remained concerned to avoid escalation of the conflict into a full-scale confrontation between Israel and the Syrians.
The Soviets clearly hope that, whatever they do or don't do, the conflict will damage United States standing in the Arab world.
One early sign of the extent of that damage -- and the extent to which Moscow might gain from it -- could come within days. Jordan's King Hussein, a traditionally pro-Western monarch who has become increasingly disillusioned with US Middle East policy, had been scheduled to visit the Soviet Union later this month. Arab diplomats here say he is weighing whether to proceed with the trip.
With the caveat that wider Mideast fighting could yet prompt widened Soviet involvement, foreign diplomats are characterizing Moscow's stand as one of general restraint.
If the Kremlin has weighed in with anything analogous to its warning of possible ''unilateral'' action during the 1973 Middle East war, the diplomatic community here is not saying so.
In Washington, Secretary of State Alexander M. Haig Jr. told a television interviewer: ''There have been two exchanges, and I would describe the Soviet attitude as encouragingly cautious.''
Among public signs of caution:
* An official statement at the start of the Israeli invasion that demanded its ''immediate cessation . . . and the withdrawal of Israeli troops,'' but did not mention Syria, which has troops in Lebanon and a friendship and cooperation pact with Moscow. The Soviets portrayed the UN as the logical instrument for countering the Israeli invasion.
* The Soviet media's tendency to portray the invasion as an assault on Lebanon and the Palestinians there, and to play down the possibility of a wider conflict.
* The lack of anything close to a pledge of Soviet military backing for Palestinian and Syrian forces against the Israelis in Lebanon.
* Moscow's first reported mission to Damascus since the invasion, made by a deputy Air Force chief, not a higher-ranking envoy.
Diplomats are watching for any hint of escalated Soviet involvement but are assuming the Kremlin remains leery of a widened Mideast war. The diplomats feel Moscow may move to resupply the Syrian Air Force, which has taken heavy losses over Lebanon, but with the understanding that the Syrians will not throw new planes into fresh battles with the Israeli invasion force.