Moscow — Tied down with troops in Afghanistan, worried about Iran, and uncertain about President Carter, the Kremlin is unlikely to launch any military activity against post-Tito Yugoslavia any time soon.
But Western experts in Moscow believe the Soviet Union might well begin exerting long-range economic pressure on Belgrade in an effort to widen Soviet influence inside Yugoslavia.
Experts also think the Soviets will have a freer hand inside the nonaligned movement now that Tito's immense personal prestige and authority are gone.
It was Tito who stood up against the argument of Cuba, Vietnam, Ethiopia, and others that Moscow is the "natural ally" of the nonaligned movement -- most recently at the Havana nonaligned summit meeting.
While predicting future Soviet behavior is risky at best, the consensus here is that the Soviets have much to lose by even hinting at military action against Belgrade.
To the Soviets the temptation is as mouthwatering as ever: access to the Adriatic Sea, new pressure on NATO members Greece and Turkey as well as on Western Europe, and an end to the aggravating Tito-stye of independence in what Stalin considered his own backyard.
But the US and Western Europe are already alarmed at Soviet missile and conventional-strength buildups. They are raising defense budgets accordingly. Medium-range missile are to be installed in NATO countries within three years.
The West is watching intently to see if the Soviets gain any significant leverage inside Iran. (Moscow has some 115,000 troops committed to nearby Afghanistan.)
To move troops toward Yugoslavia would mean risking the loss of Soviet propaganda positions in Europe. Since Romania would not permit Soviet troops to cross its territory, they would have to be moved via the Black Sea and Bulgaria, or northward through Hungary.
It would find Yugoslavia's 22 million people, already alerted by the Soviet invasion of Afghanistan, ready to fight as the partisans did against the Nazis in World War II. The Yugoslavs call it the Total People Defense Force.
Yugoslavia maintains its entire 260,000-man armed forces on its own territory. Reservists number about 500,000. No match for the Soviets in the air (330 planes versus 1,700 Soviet aircraft in Eastern Europe), the Yugoslav tactic would be to delay an invasion long enough to allow the reserves to arm and take to the mountains south of Zagreb.
A far more likely move would be for the Soviets to use their Bulgarian allies to step up pressure on the Macedonian population in southern Yugoslavia. In that way, they could exploit nationalistic divisions and split the Yuloslav union apart.
Also likely, in the short term, is economic pressure.
Yugoslavia has only observer status with the East European economic bloc known an Comecon. Comecon members buy Soviet oil at less than the current price of the Organization of Petroleum Exporting Countries. Belgrade pays the full OPEC amount -- and imports about one-third of its oil from Moscow.
Already Yugoslavia sells 41 percent of its exports to the Eastbloc. It has a foreign debt of about $13 billion. And planners are believed anxious to reduce last year's record $3.3 billion balance-of-payments deficit by cutting exports 6 percent this year.
One way to do this would be to pay lower Soviet prices for oil, and spend less money for Western imports and more for cheaper Eastern imports.
Some analysts here believe the Soviet's best choice is to expand credits for East European power plants and steel mills. They point out that although the Yugoslavs do buy much Soviet oil, they have just built a new oil pipeline from the Adriatic Sea.
Other analysts believe Moscow holds little economic leverage over Belgrade, since most of the two-way trade is on a barter basis and the Yugoslavs run a manageable deficit.
Another possibility for the Soviets would be to try to pry Yugoslavia's economically weathered southern provinces (Bosnia-Herzegovina, Kosovo and Montenegro) away from the richer northern areas (slovenia and Croatia).
Yugoslav shipbuilding exports slumped last year, and the Soviets could offer lucrative contracts.
The Soviets have cooperated in building coal-fired power plants in Yugoslavia as a way a using its coal reserves. Diplomats who have lived in Belgrade say Yugoslavian planners prefer Western technology if they can get it. But inflation and other pressures might force them back to the East bloc for more imports and technology as well.
Meanwhile, the Soviets are on notice from President Carter that any Soviet attack against Belgrade would bring a Western response. Mr. Carter promised Feb. 13 to consider military aid for Yugoslavia.