There is one issue that has the power to end the giddy international honeymoon of the last 12 months: the German question. It did more than provide an atmospheric downer to an otherwise perfectly photogenic summit. Gorbachev's apprehensions about German unification have already caused him to slow down the conventional disarmament talks in Vienna. He even threatens to slow promised troop withdrawals from Eastern Europe. Indeed, if finally resolved entirely against Russian interests the German issue has the potential to restart the Cold War.

There are only three possible states for Germany: 1) tied to the West, 2) neutral, or 3) divided against itself. (Tying Germany wholly to the East has never been within the Soviet grasp.) For 40 years, East and West could happily agree on solution 3. That solution is now obsolete. There is going to be one Germany and the only question is whether or not it will have a Western anchor in NATO.

The Soviet preference for a neutral Germany is rather hard to understand. It is a product of "old thinking," Gorbachev's term for any Soviet idea that preceded him and with which he disagrees. For 40 years, the grand Soviet strategy was to detach West Germany from NATO and induce it to neutralism. Such a Germany would have to accommodate itself to Soviet power and buy its security from Russia with money, materiel and technology. Moreover, its detachment from NATO would be a major net loss for Russia's great adversary.

Things have changed. The Soviet Union can no longer be confident that it would dominate a neutral Germany. Under the old calculation, a neutral West Germany, squeezed between East and West, would have been a vassal state. With the disintegration of the Soviet empire and with the rapid decline of Soviet power, a united and independent Germany could easily rise to its pre-war status of major geopolitical rival to the Soviet Union. Far less threatening is a Germany tied to an American-dominated NATO.

Soviet leaders are understandably skeptical when they hear hard-line pundits and presidents make this case in the name of Soviet national interests. Yet Poland and Czechoslovakia too have expressed a preference for a Germany in NATO. And when President Bush made the case to Gorbachev at the summit he coupled it with a series of concessions meant to alleviate Soviet anxieties about a NATO-allied Germany. These concessions (what The Post calls "The Nine Points") included a German subsidy for Soviet troops during their temporary stay in East Germany, a NATO pledge to keep out of East German territory, guarantees for a nonnuclear Germany and for limits on German conventional arms, and creation of a new pan-European security structure which would include Russia, America and all of Europe.

Gorbachev is still not satisfied. His strategy may be to get a neutral Germany by default. By simply stalling he can play on the considerable neutralist sentiment in Germany. His offer to Germany: You can have your unity and have us out -- if you kick the Americans out as well, i.e., neutralize. It is not at all impossible that the German electorate might accept such a deal.

This is a risky strategy for Gorbachev, however, because the threat of staying in Germany and holding up unification may stir up not just German appeasement but German resentment. In the long run, that could deeply harm Soviet interests. Which is why Gorbachev might be amenable to some kind of deal.

How to make a Germany-in-NATO deal palatable to Gorbachev? Offer to create a new pan-European institution in which the Soviet Union would play a major role. The Conference on Security and Cooperation in Europe (CSCE) encompasses the U.S.S.R., United States, Canada and all of Europe but Albania. It already has some successes to its credit. (It produced the Helsinki Final Act of 1975, the major East-West agreement in which West recognized the postwar borders in return for East's accepting certain human rights norms.) But CSCE exists largely on paper. To be presented to the Soviets as adequate compensation for a NATO Germany, it needs to be heavily tarted up.

Speaking Wednesday to the CSCE in Copenhagen, Secretary of State James Baker called it "the conscience of the continent." At the summit, Bush offered to upgrade CSCE by giving it a permanent secretariat and enlarging its areas of responsibility. We should offer more. Give it a role in arms control and adjudicating disputes between members. Endow it with a bureaucracy. Give it a less impossible name, perhaps The European League (like the Arab League or the Organization of American States, a regional body not only arbitrating problems between members but representing the region to the world).

Make a great fuss over the League. Declare it the institutional host of Gorbachev's "Common European Home." Give it whatever horns and whistles, checks and balances, Security Councils and General Assemblies the Soviets might wish. And announce that our ultimate goal -- say, in 25 years -- is the withering away of all blocs in favor of the League. In the interim, however, it must coexist with NATO (and, if you wish, the Warsaw Pact).

True, so long as the Soviets remain an adversary of the West, the CSCE/League will have little real authority. It will remain but a device to allow Russia to accept a NATO Germany. But if Gorbachev is serious about the continued evolution of the Soviet Union toward democracy and a market economy, then NATO withers away for lack of anything to do. If Russia in effect joins the West, then CSCE, now a regional bloc of like-minded, allied, advanced industrial societies, could absorb NATO.

Thus if the Soviet democratic revolution continues, CSCE will in fact answer Soviet security problems. And if the revolution fails, if Russia turns away from reform and returns to its old anti-Western antagonism, then CSCE will indeed be just a fig leaf. And we will have lost nothing by offering it.