Prospects brighten for superpower arms accord. Bonn agrees not to update Pershing 1A's, if ...

Chancellor Helmut Kohl returned yesterday from his Austrian vacation with a splash by announcing that Bonn will waive modernization of its Pershing 1A's when these missiles turn obsolete in 1991-92. Dr. Kohl set as ``conditions'' for the West German waiver real progress in medium-range arms negotiations, including not only signature but also ratification of an agreement. He also urged the superpowers to get on with strategic arms control.

Kohl presented this step as West Germany's contribution to Soviet-American agreement on eliminating worldwide all superpower intermediate-range nuclear (INF) missiles with ranges of between 500 and 5,500 kilometers (310 and 3,440 miles). The Soviets have called the 720-km-range (450 mile) Pershing 1A's the chief barrier to such an agreement.

Kohl's move, while winning West Germany some international credit, gave away nothing of substance, since Bonn had already refused, in quiet talks with Washington some months ago, to take on the domestic political fight that modernization would require.

For the moment, forfeiting modernization does not satisfy Moscow. The Soviets want the Pershing 1A's, or at least the American warheads for the West German launchers, to be included formally in the Soviet-American agreement now shaping up.

The Soviets ``think they made a great concession accepting worldwide `double zero' two times. Therefore, they now want a further concession by the US on the Pershing 1A warheads,'' explained a senior adviser to Kohl. ``Double zero'' refers to getting rid of all superpower INF missiles, in the 500-to-1,000 (310-630-mile) as well as the 1,000-to-5,500-km range.

A renunciation of the Pershing 1A's in a superpower treaty is precisely what Bonn does not want, however. ``We do not agree and cannot accept having [this] cooperative system as part of the negotiation. It is not acceptable to us or to the Americans,'' the adviser declared.

In the end, Western diplomats expect the Soviets to settle for the pragmatic solution of letting these weapons wither on the vine, especially since their demise would coincide with the five-year application of any INF treaty. Bonn government sources argue that their pledge not to modernize should thus meet Moscow's substantive demands, and they believe that Moscow wants arms control badly enough not to let joint destruction of the superpowers' more than 1,800 INF systems founder on the spat over 72 aging West German missiles.

In this context the adviser commented, ``I think [the Soviets'] main interest is to get the concession of no conversion [of American INF weapons into shorter-range or alternatively based weapons] and no modernization. This is the crucial point.'' He further suggested that the combination of the West German waiver of modernization and the American waiver of conversion already offered in the Geneva superpower negotiations should adequately cover any legitimate Soviet security concerns.

Significantly, Kohl did not tie his waiver on Pershing 1A modernization to any agreed reduction of the Soviet 300-km-range (190-mile) Scuds in East Germany and Czechoslovakia aimed at West Germany. West German officials had earlier floated the idea of such linkage, to the distress of their nuclear-armed NATO allies. Neither the United States, Britain, nor France wants to negotiate with the Soviet Union over short-range missiles with a reach of under 500 km.

In this connection, Kohl said only that he hoped the Soviet Union and its allies would respond positively to the West German example and waive future modernization of the Scuds.

Domestically, the trickiest aspect of INF arms control for the center-right Bonn government at this point is the need to keep West German conservatives from feeling deserted by the US in any deal and from suspecting that the American nuclear guarantee is being pulled out from under them. Over the summer, Kohl's staff has worked hard to dampen this emotional reaction in the ranks of the government's main coalition parties. Kohl's aide saw ``the main danger'' at present in a ``process of beginning alienation between conservatives in Germany and the US because of `double zero.'''

``If this process of alienation continues,'' the adviser feared, then a dangerous resentment of the US will build up both ``on the left and on the right. Therefore, I am happy - satisfied that the American administration seems to understand the importance of not giving up the Pershing 1A.''

It was alarm within the center-right's own ranks that prompted the West German government to hang on to the Pershing 1A's last spring despite the missiles' limited military value and to insist that they not be traded away in INF arms control.

The sensitivity arose from the potential impact of a ``double zero'' going down to the 500-km range in leaving the two Germanies exposed, uniquely among their allies, as the geographical area that would be almost the sole target for the remaining short-range nuclear missiles.