During last month's debate on the defense authorization bill, Congress demonstrated an unprecedented concern for the twin issues of arms control and nuclear stability. Unfortunately, the furor over the MX, antisatellite weapons, and ballistic missile defense all but obscured any examination of what promises to be one of the most expensive and destabilizing weapons of this decade. This year's bill provides funds for the initial procurement of the Trident II submarine-launched ballistic missile (SLBM). The introduction of more than 800 of these missiles, as well as their inevitable Soviet counterparts, will usher in a dangerous era of strategic vulnerability and instability.
Hoping to avoid the controversy that surrounds the MX, the Navy often describes the Trident II - also known as the D-5 - as the ordinary modernization and replacement of the existing Trident I missile. Yet there is a dramatic difference in the two missiles' military capabilities and strategic implications. With its long (4,000-mile) range and eight warheads, the Trident I is a classic retaliatory weapon, a missile whose ability to destroy a range of economic and industrial targets provides a highly survivable and powerful deterrent.
In contrast, the Trident II represents the ultimate counterforce weapon. Constructed to take full advantage of the Trident submarine's large dimensions, each missile will pack eight to 10 warheads with a lethal combination of high yield and accuracy, surpassed only by that of the MX. Unlike the MX, however, the Trident II will be able to hit Soviet targets within 10 to 15 minutes after launch from submarines based in the Atlantic, Pacific, or Indian Oceans. Moreover, with the completion of 20 Trident submarines in the late 1990s, more than 3,000 of these warheads will be within striking distance of the Soviet Union at any time.
This sort of capability is more than enough to destroy the entire existing force of Soviet ICBMs. Because of the missile's very short flight time, it could also simultaneously threaten Soviet strategic bombers. With its potential for carrying extremely accurate and versatile maneuvering reentry vehicles (MARVs), the Trident II - by any criteria - has all the makings of a potent first-strike weapon.
The requirement for such ''hard target'' capabilities has centered on the perceived need to counter Soviet MIRVed ICBMs, and their threat to American land-based forces. In particular, it is argued that the deployment of new US missiles will force the Soviets into less menacing systems, such as small ICBMs and SLBMs. A program that promises to threaten the majority of Soviet strategic systems, however, is not likely to move the Soviets away from the large ICBMs that have historically represented the backbone of their nuclear deterrent. Indeed, Soviet development of two new ICBMs, the MIRVed SS-X-24 and the single SS-X-25, indicates a continued interest in large ICBMs as well as small, mobile ones.
More important, the introduction of the D-5 will actually spur the development of comparable Soviet SLBMs, capable of attacking a range of targets from submarines parked off American shores. Although the United States holds a definite technological and operational lead in submarine-launched missiles, the Soviets can be expected to introduce a similar missile soon after the introduction of the Trident II. In a world of fast, accurate submarine-launched missiles, both sides may face a ''double window of vulnerability,'' in which ICBMs and bombers remain susceptible to sea-based attack. With only minimal time for early warning, assessment, and response, both sides will thus be drawn that much closer to the brink of accidental nuclear war.
We should not make the mistake - already committed with MIRVs and cruise missiles - of introducing a new system with the expectation that it will give us a longstanding advantage. It is not too late to negotiate a ban of new SLBMs with the Svoiets, who have already indicated an interest in such a proposal. The alternative involves an extravagant expenditure, and another step away from nuclear stability toward strategic uncertainty.