US views Soviets' latest arms proposal. Though disappointed, officials welcome Soviet readiness to haggle

The latest Soviet proposal on deep cuts in strategic offensive arsenals is a bad one - but an encouraging sign. This is the paradoxical analysis of Western officials as Washington and Moscow gear up for their off-again-on-again summit that begins Dec. 7.

As one Western official explains it, the Soviet offer on the key issue of offensive warhead ``sublimits'' is disappointing, since it is far from a reasonable negotiating position at this late stage in talks. But it is very welcome after a long year in which the Soviets would not even address the issue in the Strategic Arms Reduction Talks (START). The proposal signals they have finally started the real haggling.

Moscow refused until last September to admit that sublimits were necessary under the overall reductions agreed to at the Iceland summit a year ago. Those reductions would bring stocks down to 6,000 warheads and 1,600 launchers (missiles and bombers) each.

The Soviets first moved on sublimits when Foreign Minister Eduard Shevardnadze visited Washington in September, and more progress was made a week ago during Secretary of State George Shultz's Moscow visit.

In Moscow, the Soviets offered new limits on the numbers of warheads in three categories: 3,000-3,300 on intercontinental ballistic missiles (ICBMs); 1,800-2,000 on submarine-launched ballistic missiles (SLBMs); and 800-900 on air-launched cruise missiles (ALCMs). They earlier had promised that in any deal their heavy SS-18 missiles would be reduced to no more than 1,540 warheads and would not later be increased.

The US proposal made a year ago in the Geneva negotiations includes a total ceiling for ballistic missile warheads of 4,800; a maximum of 3,000-3,300 of those could be ICBM warheads, with a maximum of 1,650 allowable on heavy missiles or missiles carrying more than six warheads a piece (the Soviet's SS-18s and mobile SS-24s, and the US's MX missiles).

The newest Soviet proposal is unacceptable to the US for two reasons. First, the sublimits are rigid, favoring, of course, the particular Soviet mix of weapons and giving the US no freedom to choose its own apportionment. They would require the US to restructure drastically its whole strategic arsenal. Second, forcing the Soviet mix onto the US would perpetuate rather than redress the current ``instability'' in strategic postures that the arms control talks are seeking to correct .

The US figures, though favoring the US mix of weapons, are not as lopsided and allow both sides flexibility.

The differences arise from Moscow's greater reliance on ICBMs (some 64 percent of its strategic inventory) and Washington's greater reliance on SLBMs (58 percent) and bombers (22 percent).

The Soviet Union would like to maneuver the US into reducing its submarines, which for decades have been much quieter and better able to hide than Soviet subs. The US would like to maneuver Moscow into reducing the number of SS-18 ICBMs, which could easily loft 25 or 40 warheads each were they not restricted to 10 by the Strategic Arms Limitations Treaty of 1979 (SALT II).

The aim of the US proposal is not only to halve strategic warheads, but also to ensure that those removed are on the big, highly accurate, silo-based ICBMs - the most threatening but also the most vulnerable weapons. They are considered the least ``stable'' weapons, since in any crisis there would be a temptation to launch them in a ``preemptive'' attack to avoid having them destroyed in any attack by the adversary - the ``use 'em or lose 'em'' syndrome.

Much more stabilizing in any crisis are strategic weapons that are ``survivable.'' These are weapons less vulnerable to surprise attack because they would be in motion rather than in a fixed base, and could not be easily found nor targeted. SLBMs, bombers, and mobile missiles fall in this category.

Western officials contend the new Soviet figures show the Soviets could in fact live with the US's proposed sublimits, since both now have compatible offers in the category of ICBM most critical for Soviet forces. The Soviet ceiling of 1,540 warheads on heavy missiles basically meets the overriding US concern about these weapons, and the Soviet and US maximums for total ICBM warheads (3,300) are identical.

This leaves only the Soviet attempt to win disproportionate reductions in ALCMs, and especially submarines, as problematical for the US force structure. The 900 ALCMs the Soviets would allow on bombers are not far from the 1,000 ALCMs the US would wish to deploy in a 6,000-warhead inventory. But 2,000 SLBM warheads are still far from the 3,600 the US would deploy if it distributed its 6,000 total warheads over the land-sea-air triad in the same ratios as at present.

Other outstanding issues in START include ``throw weight'' and mobile missiles. Under 50 percent cuts, Moscow would be willing to halve the total throw weight its missiles could launch - a capability currently much greater than the US's equivalent. But Moscow is not ready to write this into a treaty, while Washington wants to codify it. On mobile missiles, the US seeks a ban, while the Soviet Union wants to allow them.