Soviets Seek 50% Nuclear Arms Cut : But Offer to President Fails to Deal With Key U.S. Point of Weapons Mix

The Soviet arms reduction offer handed to President Reagan on Friday by Soviet Foreign Minister Eduard A. Shevardnadze went somewhat further than Administration officials had expected, calling for a 50% cut in nuclear warheads and bombs, but it did not contain another feature that they consider crucial in any major arms control plan.

Contrary to earlier signals, the officials said, the plan presented to the President by Shevardnadze did not specify that no more than 60% of a nation’s total nuclear forces could be concentrated in one type of weapon--land-based missiles, sea-based missiles, or bomber-carried weapons.

This point is vital to the United States, in the view of Administration arms specialists. Even more than a cut in total weapons, the Administration wants to reduce the threat of a surprise attack by the huge Soviet force of land-based intercontinental missiles. About 70%-75% of the total Soviet nuclear force ride on these fast-flying, highly accurate ICBMs, while U.S. strategic weapons are spread more evenly among submarines, bombers and missiles.

Notable Exclusion

Shevardnadze’s failure to include a limit on land-based missiles was particularly notable because other major provisions of the plan he delivered followed closely the earlier signals from the Kremlin.

Before the meeting at the White House, Moscow had indicated that it might suggest a 40% cut in strategic weapons--only slightly smaller than the 50% cutback plan the new Soviet foreign minister brought to Washington. Also, as expected, the Soviet official made it clear to Reagan that the deep cuts were contingent on tight restrictions on the Administration’s Strategic Defense Initiative, the so-called “Star Wars” program that Reagan says is intended to determine whether a space defense against enemy ballistic missiles is possible.

Cutting the superpower nuclear arsenals by half has an immediate and instinctive appeal, and Reagan himself Saturday took care to welcome it. Specialists pointed out, however, that when it comes to strategic weapons and nuclear deterrence, things are seldom as simple as they seem.

First Strike Fears

In particular, U.S. arms experts are concerned about the mix of kinds of weapons that each side might be left with if a 50% cutback were made. Modern land-based ICBMs--each with multiple warheads of enormous nuclear power--are so fast and accurate that they raise fears of a first strike. They are more destabilizing than present-day submarine missiles or bombers, which are difficult to communicate with or not fast enough to strike an enemy before he could assess the situation and decide to launch his own missiles.

Thus, an arms agreement that left only land-based ICBMs would result in a less safe rather than a more safe world, according to U.S. strategists.

The maximum percentage of weapons to be permitted in any one category, therefore, is certain to be a key number awaited by U.S. negotiators at the Geneva arms talks this week when the Soviets give details of their proposal--or “counterproposal,” as President Reagan termed it Saturday, since the United States had made a detailed strategic arms offer three years ago.

That U.S. proposal called for a 33% cut in warheads on land- and submarine-based ballistic missiles (no bomber-carried weapons were included), with a maximum of 50% of the missile warheads permitted on the land-based ICBM’s.

Senior-Level Meetings

In his weekly radio address Saturday, Reagan also said that he and Shevardnadze “agreed to set up a series of senior level discussions between our experts in preparation for the Geneva (summit) meeting” Nov. 19-20 between Soviet leader Mikhail S. Gorbachev and Reagan.

Another point that was unclear from Shevardnadze’s presentation to Reagan was whether the same 50% cut in nuclear forces would apply to both the United States and the Soviet Union. The totals are considerably different today, with the United States having the larger arsenal--some 12,200 nuclear bombs and warheads that can hit the Soviet Union, compared to about 9,900 for the Soviet Union that could strike the United States.

A 50% cut in both would leave the United States with about 6,100, and the Soviets with about 4,950. But it would be extremely surprising if Moscow accepted a lower ceiling on its own weapon total than the United States.

Shevardnadze mentioned that both sides should have equal levels at the end of the reductions, which reportedly would be spread over five years.

Possibilities Explored

One possibility is that the detailed Soviet proposal will call for a cut of 50% in the largest arsenal--the U.S. force--to the 6,100 limit, with that limit then applying also to the Soviet force.

But in any case, Moscow’s offer clearly implies that the United States would have to give up more of its nuclear warheads and bombs than the Soviet Union, because it has more.

The Soviets use the word “charges” to cover both nuclear bombs and warheads, and Shevardnadze said that by Soviet accounting, the United States has about 12,000 such “charges.” Such a number can be obtained by adding up this country’s 2,120 ICBM warheads, 5,800 submarine-based missile warheads, the 1,100 bomber-carried cruise missiles, and 2,100 bomber-carried gravity bombs and short-range attack missiles. This totals 11,120, but another 1,200 “phantom” warheads are credited to submarine-based missiles.

These “phantoms” occur because all missiles are assumed, under existing strategic arms agreements, to carry as many warheads as the maximum number with which they’ve been tested. This maximum figure is 14 warheads for the C-3 Poseidon missile, although it usually only carries 10 warheads, plus several lightweight decoys to help its penetration and to give the missile greater range.

The comparable Soviet break-down is 6,420 land-based missile warheads (which probably includes some “phantom” warheads for the same reason), 2,800 submarine-based missile warheads, 150 air-launched cruise missiles, and 530 bombs and short-range attack missiles, according to a compilation by the Arms Control Assn.

If the 50% reduction in nuclear “charges” sets a ceiling for both sides of 6,100, and if Soviets next week do propose a 60% limit on the proportion of nuclear “charges” that can be placed on any one leg of the three-legged strategic arsenals, then Soviet land-based ICBM warhead ceiling would be 3,660 warheads, a drastic reduction from its 6,420 level today.

ICBM Cuts Possible

This reduction would require cuts in the numbers of those ICBMs that are both the most modern and the most threatening of Soviet weapons: the 308 SS-18s with up to 10 warheads each, and the 360 SS-19s with up to six warheads each.

These two missiles ostensibly carry 5,240 warheads, but discounting “phantoms,” they probably carry about 4,500. Thus, even if the older Soviet ICBMs were first eliminated, some of these SS-18s and SS-19s would have to go to reach the 3,660-warhead ceiling.

Moreover, according to analysts, the Soviets have two new mobile ICBMs in production, the SS-24 (with 10 warheads) and the SS-25 (with one warhead). It is doubtful that the Soviets would decide not to produce these newest missiles, so as they are introduced, the number of SS-18 and SS-19s could be reduced further.

Such radical reductions would also affect the most modern U.S. weapons that are only now being developed and deployed, and the Pentagon would face hard choices about which systems to retain.

When the 14-warhead Trident D-5 missile is deployed on submarines, for example, it will replace 288 eight-warhead C-4 missiles, thereby adding 1,728 more warheads to a weapon category which, at 8,000, already exceeds the prospective ceiling.

In addition, the 50 new MX ICBMs, each with 10 warheads, are replacing 50 three-warhead Minuteman ICBMs, thereby adding 350 more warheads to the current U.S. total of 2,120 on those missiles.

So if the number of U.S. submarine-launched warheads was reduced to the 3,660 ceiling, and if all of the 2,470 fast-flying ICBM warheads were kept, the Pentagon would have to scrap all U.S. bombers with their sophisticated new cruise missiles as well as their other nuclear weapons.