Moscow is showing its first flexibility in the intermediate-range nuclear (INF) arms control negotiations. And this means the real battle for President Reagan's ultimate arms-control policy will soon be joined, both in Washington and within the NATO alliance.
This is the interpretation that a number of diplomatic and other observers in Europe put on the New York Times report of Moscow's late-November feeler at the US-Soviet INF arms control talks in Geneva.
As reported by the Times, Moscow is now suggesting reduction of its existing nuclear missiles aimed at Europe to some 150 or 160 - within a global total of about 250 Soviet intermediate-range missiles - if NATO will forgo its new Pershing II and cruise missiles planned for deployment from the end of 1983 through 1987.
The feeler - it cannot be determined here whether a formal offer is involved - contains possible new elements. But much ambiguity remains. The new elements of Soviet flexibility include potential willingness:
1.To focus on missiles and deemphasize aircraft at this stage.
2.To allay Western collateral concern about Soviet mobile missiles now aimed at China that could be moved to bear on Europe, (by hints of freezing the Asian component at about 100).
3.To allay Western concern about Soviet ''circumvention'' of any eventual INF balance by a buildup of 1000-kilometer SS-22 and other missiles below the intermediate range (by hints of a freeze in this category).
In addition, there may be some Soviet movement toward the Western insistence on exclusion of the independent French and British nuclear forces from the US-Soviet nuclear balance in Europe.
The new Soviet feeler ensures that missiles and arms control will be a key issue in the West German election planned for March 6. And it opens the potential for new US-West German strains in security affairs.
The intra-alliance debate that has already begun does not concern the Soviet offer as such; the NATO allies agree that the Soviet numbers are still far too disadvantageous for the West to accept. Instead, the argument pits those who want to reject the Soviet feeler categorically against those who want to explore it and at some point modify Washington's opening ''zero-zero'' proposal to a ''zero-plus'' offer meeting the Russians partway.
Reagan's zero-zero position as the talks opened a year ago called for forfeiture of the planned new NATO INF missiles in return for the destruction of already deployed Soviet INF missiles - including especially the 5,000-kilometer, three-warhead, mobile SS-20s that became operational in 1977 and triggered NATO's 1979 INF plans in response. Zero-plus would mean that some but not all SS-20s would be dismantled, while some but not all of the planned NATO missiles would be deployed.
Basically, this duel will be fought out in Washington, between the Pentagon - which has insisted from the beginning that zero-zero must be immutable - and the State Department, which has regarded a compromise offer as essential at some point both to satisfy the European allies and to persuade antinuclear movements in Europe of US good faith in negotiating.
Europe does have a vital interest in the Pentagon-State confrontation, however, and has already begun to put a discreet finger on the State Department side of the scales. British Defense Minister John Nott and NATO Secretary-General Joseph Luns have publicly foreshadowed a future shift in the Western position, and some lower-ranking West German officials have done the same privately.
US Defense Secretary Caspar Weinberger shot down such speculation at the NATO defense ministers' summit in Brussels the first week in December, in effect telling the Europeans to leave the negotiations to the US.
At this point West Germany is an uncertain factor in the whole equation. Social Democratic ex-chancellor Helmut Schmidt played a key role a year ago in getting a reluctant Moscow and a reluctant Washington to the INF negotiating table in the first place. And in a recent interview with a West German newspaper , Mr. Schmidt again spoke of the need to keep the pressure up on both superpowers to get on with arms control.
By contrast, the incumbent conservative Chancellor Helmut Kohl is not personally engaged in arms control. He has not made any particular public statements on the subject nor - according to a source who was present at one such conversation - does he ask penetrating questions of American officials who brief him on arms control.
There are strong pressures on Chancellor Kohl to promote arms control more actively, however. Domestically, these include both the coming election campaign and the West German antinuclear movement - which fielded several tens of thousands of demonstrators Dec. 12 to hinder access to 40 American and West German missile bases.
Internationally, they include as well the desire to maintain good relations with the Soviet Union, and to make a success of Soviet Foreign Minister Andrei Gromyko's Bonn visit next month.
For now, West Germany and the other allies unite with the US in rejecting the new Soviet feeler as too lopsided.
It is, to be sure, an improvement over the opening Soviet position of 300 nuclear launchers each for NATO and the Warsaw Pact, including French and British as well as American NATO systems in the count. That proposition would not only have left Soviet SS-20s virtually intact, while allowing NATO nothing new; it would also have confined European theater nuclear defense basically to the British and French systems and would have even required withdrawal of American INF (aircraft) systems already in place.
This would have weakened not only NATO nuclear defense, but also its conventional defense, since those bombers are dual-capable, for either conventional or nuclear loading.
In terms of the negotiations themselves, the earlier Soviet position would also have ensnared the INF talks in the thicket of aircraft numbers, where there is wide disparity in the data base of the two sides and the complexities of any agreement would consume years at the negotiating table. In missiles the two sides' numbers are quite close and have been ever since the talks began.
Nonetheless, the new Soviet suggested ceiling of some 250 INF missile launchers would still leave the Soviet Union far ahead, in Western analysis. Under it the Russians would dismantle their 260 old SS-4s and SS-5s - which they were going to do anyway - and about 90 to 100 of their almost totally deployed complement of 350 SS-20s. This would still leave them some 250 SS-20s in both Asia and Europe, with some 150 to 160 of these able to target any spot in Europe with 450 to 480 high-accuracy warheads with assured penetration on a flight trajectory lasting only minutes. NATO would have no equivalent, since its 20 -year-old land-based Pershing I missiles do not come anywhere near reaching Soviet territory.
France's 18 non-NATO single-warhead SSBS S-3s would then be the only land-based missiles in Western Europe capable of reaching the Soviet Union. This would make a very skewed balance of 450 to 480 highly accurate, 5,000-kilometer mobile and therefore invulnerable Soviet INF-warheads vs. 18 much less accurate, 3,000-kilometer, immobile and therefore vulnerable Western European INF warheads.
It is not yet completely clear whether the latest Soviet feeler would include or exclude French and British nuclear missiles in counting the Western counterpart of the 150 to 160 Europe-targetable Soviet missiles. (The figures of 150 to 160 are ones the Soviets have cited several times in rule-of-thumb calculations of the French and British systems.)
Even if they are included, the crucial resulting warhead balance would still heavily favor the Warsaw Pact, since the Soviet launchers would each carry three warheads, while the Western launchers carry only one. If the British submarine and the French submarine- and land-based missiles were all included (as well as the Soviet submarine nuclear missiles not counted as strategic weapons) the West would then still have only 162 European-theater warheads, as against the Soviet Union's 468 to 498.