Behind the brooding, fortress walls of the Kremlin, Soviet leaders con front their most crucial question in Eastern Europe for more than a decade: Just how far can they let the defiance of Polish workers go?
The answer -- shaped partly by the sudden meeting of Polish and Soviet party leaders in Moscow Oct. 30 -- will determine much more than whether the Polish trase union called Solidarity will be legally registered, or whether workers will eat more meat and keep on listening to Roman Catholic mass on the radio on Sundays.
How the Kremlin reacts will determine whether detente between the Soviet Union and the United States, already at its worst for 12 years, has any chance of an early recovery.
A Soviet invasion of Poland remains a last resort. It does not seem immiment. Signs are that the Polish leadership is urging the Politburo of Leoniz Brezhnev to understand that dialogue with the workers in Gdansk is the only way to avoid more strikes and confrontation.
Moscow does not want to invade. It would be a war with no holds barred. No one would really win. The Soviets would prevail by force of arms -- and then have to run a bankcrupt economy and a people seething with hatred for their occupiers.
More than that, Soviet tanks in action against Polish "freedom fighters" would explode lingering hopes that the US might ratify the SALT II treaty, that the spirit of Helsinki might yet bear more fruit at the review meeting in Madrid next month, that a new superpower arms race can be avoided.
The challenge for the Kremlin is to stay calm and continue its strategy of restraint.
So far it has combined heavy backstage pressure on Stanislaw Kania, the chief of Poland's Communist Party, with judicious amounts of economic aid including wheat, and support for moves to isolate East Germany, the key frontline state of the Warsaw Pact, from possible contamination.
Moscow has signaled in the Soviet press that Poland cannot be permitted to leave the Warsaw Pact or let its Communist Party lose control. Every Pole knows that strung across southern and central Poland are the railroad and other supply lines that link the USSR with the 19 crack Soviet divisions in East Germany.
Moscow will permit no interference with these lines, which are permanently guarded by two Soviet Army divisions.
Polish leaders must play a subtle game, supporting concessions to the workers in public while privately telling the Soviets the concessions will be kept within bounds and no more will be allowed.
The Oct. 30 meeting in Moscow came just one day before Premier Jozef Pinkowski was to meet Gdansk strike leader Lech Walesa. It also came amid clear signs of rifts within the independent trade union.
The meeting seemed designed as a warning by the Kremlin to both Mr. Kania and Mr. Walesa and his Solidarity union.
To Mr. Kania, the Soviets were in effect issuing a reminder that Moscow is worried and determined not to permit developments that would give other parts of the Soviet empire the impression the Soviet hold over its allies was slipping.
O Mr. Walesa, the Soviets were saying that enough was enough, that there were limits beyond which not even the Solidarity union could go.
The meeting came after both the Polish government and the union had shown some flexibility in arranging a meeting with Premier Pinkowski. The union had voted to demand that Mr. Pinkowski go to Gdansk. He sent Deputy Premier Mieczyslaw Jagieski instead, who managed to arrange that a delegation of workers would go to Warsaw to see the premier Oct. 31.
It is this kind of compromise that has kept the Russians at bay so far.
Both Mr. Kania and the Solidarity union threatened to end compromise. n Oct. 24, the Warsaw district court summarily rewrote the articles of the union -- which claims 7 to 8 million members, more than half the 13 million Poles in the socialized sector -- to include recognition of the "leading role" of the Communist Party.
It was a blunt move that angered hard-lingers in the union, especially the militant Gdansk chapter. A "strike alert" has been called for Nov. 12. The union continues to argue over the wisdom of another major strike.
Polish leaders can tell the Kremlin that Mr. Walesa has said publicly he does not want to upset Polish alliances, but only to clean house internally.