Counting Andropov's SS-20s: why the West bargains tough

The Soviet Union's offer to reduce intermediate-range nuclear missiles aimed at Western Europe puts the United States in a delicate bind.

Washington officials - as well as European allied leaders - are forced to reject it initially and publicly, since the proposal would leave the Soviet Union with as many SS-20 rockets as (if not more than) it had when arms-control talks began in Geneva 13 months ago. If that number (250) was not acceptable to the West going into the talks, officials ask, how can it be acceptable now?

Yet, Soviet leader Yuri Andropov in his speech this week has made an important offer, American arms controllers concede, albeit one that lacks vital details that will have to be thoroughly explored when Intermediate-range Nuclear Forces (INF) discussions formally resume Jan. 27.

Behind the Andropov speech and the initial prickly US response, one official notes, the INF arms parley is ''where the most fascinating negotiations are going on.''

''Negotiations are at a delicate stage,'' says an American close to the Geneva talks. ''They have indeed changed from their previous position, but in ways that are typically Soviet.'' This, he explains, means an offer made for public consumption that contained as many questions as answers and left room for pulling back.

''Will they do that in this instance?'' the official asks. ''There's no way of knowing until we go back (to Geneva).''

The Americans see two major problems with the Andropov proposal, which in essence reiterated early Soviet statements at Geneva and is designed to prevent planned deployment by NATO of 108 Pershing II missiles and 464 cruise missiles beginning in late 1983.

Superficially, it would leave the Soviets with fewer nuclear delivery vehicles and less explosive power directed at Europe. But the new SS-20s, with three warheads each, have much greater range and accu-racy than the older missiles they are replacing, and thus are more threatening.

At the moment, the Soviet Union has deployed 333 SS-20s, about 100 of these in Asia and the rest targeted on Europe. Reducing the number of missiles aimed at the West would be welcome, officials say, but what about the missiles east of the Ural Mountains? These still threaten Japan and Korea and in fact could reach NATO members Norway and Turkey.

Mr. Andropov this week made no mention of what would happen to the missiles moved from European Soviet soil. Would they be dismantled, or merely moved east to a point from which (since they are highly mobile) they could quickly be used to threaten or attack Western Europe? US intelligence has established the location of SS-20s and tracked them as they are moved about.

The Soviet offer to reduce deployed SS-20s to match the number of British and French nuclear forces is seen here as one-sided, an attempt principally to divide the NATO alliance.

Between them, Britain and France have 162 nuclear missiles with a total of 290 warheads. A comparable number of Soviet SS-20s would have 486 warheads. Beyond this, all but 18 of the British and French missiles are aboard submarines , which means they are less accurate and less able to respond quickly to a nuclear attack. They also have a shorter range than the SS-20. Both Britain and France plan to upgrade their nuclear capabilities in coming years, but the position here is that these are independent deterrent forces and not necessarily part of a unified NATO military structure.

''You have to ask why they were willing in the past to come to agreements with the United States without taking the British and French systems into account,'' says a senior administration source.

As for Andropov's pledge to build cruise missiles and a new strategic weapon to counter the land-based MX, US officials see nothing new. Although it remains at least several years behind the US, the Soviet Union ''already has a substantial force of cruise missiles,'' says a senior State Department official. And according to US intelligence sources, a new and more advanced Soviet land-based ballistic missile already is being developed.

If the Andropov speech is designed to influence European public opinion, the Reagan administration opinion also faces domestic political pressure regarding new intermediate range missiles. In the appropriations bill passed this week, Congress deleted funds for the Pershing II pending better flight test results. The missile flunked its first two tests and did not meet full expectations on the third.