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THE CREDIBILITY OF OUR SSBN DETERRENCE

Can the OHIO-class SSBN, armed with the D-5 (TRIDENT-II) missile, be relied upon to execute all strategic options assigned? Until recently, conventional wisdom suggested that the SSBN was invulnerable. However, detractors claim submarine launched ballistic missiles (SLBMs) are not as militarily capable as land-based ICBMs; and the communications links to the U.S. SSBN force are fragile. By this rationale, the submarine leg of the Triad would not be as capable or reliable as the ICBM and air breathing systems — bombers and cruise missiles — under wartime stress, or when it really counts.

It needs to be argued that the OHIO-class SSBN with the TRIDENT-II weapon system can successfully execute all strategic missions assigned as well as, if not better than, land or air systems. This can be shown by discussing SSBN hardware, listing SSBN strategic missions, and then assessing the TRIDENT-II system’s ability to fulfill these missions in terms of the SSBN’s capability and survivability, the D-5 missile’s penetration and performance characteristics, and lastly, communications vulnerability.

The USS OHIO-class submarine exceeds design specifications in both performance and quietness. The navy presently wants 20 OHIO-class SSBNs, 10 each for the Atlantic and Pacific Fleets. The 16th ship was funded in the FY-89 budget and the remaining four seem a certainty. All of these strategic submarines are designed for a 70/25 day deployment/turn-over cycle. Today, OHIO-class SSBNs are armed with the TRIDENT-I (C-4) ballistic missile. The USS TENNESSEE is scheduled to reach initial operational capability in December 1989 armed with the first load of D-5 SLBMs. By 1989 the D-5 missile production line will turn out about six missiles per month until the entire OHIO class is fully equipped.

The D-5 is a 44-foot long, three-stage missile with a range of about 6,000 miles. Each missile will carry 8 multiple independentlytargeted re-entry vehicles (MIRVs), although it could carry more. The ninth of 20 scheduled missile tests from land-launch pads was completed on 21 January 1988 with a record of eight successes and one failure. The system is “on track” and the navy claims the D-5 can match the targeting capabilities of land-based ICBMs.

The D-5 will deliver a larger payload with better accuracy than the C-4 missile. It will create a hard-target capability from launch ranges that insure SSBN survivability now and into the future. The SSBN can utilize the NAVSTAR system. With existing on-board position-keeping qualities, own ship’s location within 10 feet is guaranteed. Improved submarine position fixing and the midcourse stellar UP-dates of the D-5 missile will insure that eight 150 KT highly accurate reentry vehicles can be delivered on target at ranges up to 6,000 nm’s. To achieve a hard target kill capability, a larger and heavier high-yield warhead, the MK-5, is being developed. With the MK5, the same number of reentry vehicles on the C-4 become hard target capable at 4,000 nm’s. As usual, throw-weight versus range are trade-offs.

Strategic nuclear options available to the Joint Strategic Target Planning Staff include variations of both counterforce and countervalue targeting. Counterforce attacks include:

  • A First Strike Disarming Attack,
  • Launch On Warning (LOW),
  • Launch Under Attack (LUA),
  • Limited Nuclear Options (LNOs)
  • Prompt Hard-target Retaliatory Attacks, and
  • Intrawar Fighting.

The “first strike” and launch-on-warning are preemptive attacks planned and executed in a┬ápeace-time environment. Both are possible, but highly unlikely actions by the u.s. The remaining counterforce options are most likely to occur in a nuclear environment where only the SSBNs at sea are invulnerable to attack (permitting their missiles to be withheld); and where the SSBNs remain durable for months, not hours as are manned bombers in flight. Nation-wide communications disruption is probable in a nuclear exchange because the electromagnetic pulse CEMP) from a high-altitude nuclear detonation can produce total electrical power outages. Also, physical destruction of communication facilities from weapon blast is likely. This disruption across the entire electromagnetic spectrum will affect ~ communications to satellites attempting to relay messages to any surviving strategic forces. Reconstitution of communications, “one-way” for submarines, appears a key to conducting successful war fighting with surviving strategic forces.

Countervalue attacks deal with:

  • Retaliatory Attack by U.S. SSBNs, and
  • War Termination Bargaining.

Both these options depend upon survivable forces, but are not necessarily time-sensitive. Certainty of retaliation is the real deterrent, not the exact time it will occur. It follows that if sometime during an SSBN’s 70-day patrol a properly authenticated emergency message is received from the national command authority, a retaliatory attack will take place.

SSBNs at sea maintain prelaunch survivability through mobility in ocean space. Their ballistic missiles are difficult to defend against for the same reason — the position location uncertainty of the launching platform. SSBNs can operate in the vast regions of ocean-space and launch missiles from many azimuths at their targets. On the other hand, the location of ICBM silos are well known and the missile flight-paths approximate a great circle to the target. Since the enemy has a good sense of what is being targeted, his active defenses can be positioned in the best locations.

Should deterrence fail, ballistic missiles from forward deployed u.s. submarines, having a short time-of-flight, could be the first strategic weapons to arrive on target. Because of SSBN survivability, withheld missiles could be available for retaliatory strikes, or saved for war termination bargaining. The manned bomber, of course, also can attack from various azimuths, but it has limited airborne endurance and is more detectable than the SSBN prior to weapons launch.

To appreciate the enormous patrol areas available to the SSBN, 71 percent of our planet is covered by water with a volume of 360 million cubic miles. All the world’s population — some four billion people — would not displace a single cubic mile of sea water. In this vast space, the OHIO-class SSBN, carrying the TRIDENT-II missile, can patrol under some 50 million square miles of ocean surface. Close to merchant traffic, naval formations, fishing boats, sea mammals and miscellaneous flotsam and jetsam, locating, classifying and attacking the submerged SSBN is analogous to locating a needle in a haystack.

U.S. submarine security has outdistanced U.~. and Soviet anti-submarine warfare capabilities. The ongoing SSBN Security Program incorporates indepth intelligence, laboratory experiments, mathematical models and real-world tests to identify and evaluate potential submarine threats. Technologies with a potential to threaten our SSBNs are not only assessed, but countermeasures are developed before a need arises. Critics of the “blue-water” deterrent raise the possibility of a “transparent ocean,” but there simply is no credible evidence to indicate that technologies to do this are even on the horizon.

Communication reliability between the National Command Authority and the u.s. SSBN force under conditions of wartime stress is often questioned by strategists and politicians. Redundant worldwide communications are in place. Submarine UHF, HF, LF, VLF, ELF, the USAF,s National Emergency Airborne Command Post and Emergency Rocket Communications System, Strategic Air Command Airborne Command Post, the Defense Satellite Communications System and the Navy’s E-6A TACAMO aircraft system, exist and work.

The primary world-wide “receive only” method of communicating with submarines at sea is the very-low frequency (VLF) network. This system consists of two primary and seven back-up sites in the u.s., and another primary site in Australia. The submarine receives a VLF signal on its underwater loop antenna down to a depth’of about 150 feet. The submarine also can receive the VLF signal on its submerged trailing-wire antenna or by raising an antenna above the surface on a hydraulic mast. At deeper depths the submarine can stream an antenna buoy that floats to the surface. VLF sites are “soft” targets, and like many other communications, can be affected adversely by electro-magnetic effects from nuclear bursts.

As “insurance,” the navy operates two squadrons of TACAMO aircraft that fly continuous random patterns over the Atlantic and Pacific Oceans providing VLF relay capability. These aircraft operate under conditions of electronic silence and guard multiple sources for emergency action traffic. The E-6A aircraft can remain airborne for up to 72 hours providing additional communications survivability, since TACAMO, — far at sea — is not likely to be affected by nuclear detonations on or over the United States. As further “back-up,” the VLF network is augmented by many low frequency transmitters in and outside of the u.s.

The extremely low frequency (ELF) system provides low data-rate alerting information for submarines operating at varying depths or at high speeds. Although the transmitting sites are not hardened, this system is not susceptible to electro-magnetic pulses or jamming. When the submarine hears an alerting sequence or loses the continuous broadcast signal, it may come to communications depth and monitor other navy, air force and joint command frequencies. Since most analysts consider an “attack from the blue” the least likely of all nuclear war scenarios, probability is high the ELF system will provide the SSBN force with strategic warning.

Submarines can receive traffic on ultra-high frequencies via four satellites in the FLTSATCOM system. When the MILSTAR system becomes fully operational in the early 1990s, SSBNs will have another satellite communication option that is jam proof through frequency-shifting techniques, and placed at an altitude higher than anti-satellite systems now operate. Also, laser communication systems are in research and development for future submarine applications.

Does streaming a trailing wire antenna, communications buoy or raising a whip antenna mean that the SSBN will be detected? Not likely, considering the size of the antennas versus the surface area of the ocean. Neither does enemy jamming pose a real threat since the SSBN is operating closer to one or more of the world-wide system of U.S. transmitters than to Soviet jammers.

The issue, however, is how useable are these systems in a nuclear environment? The Navy is confident that some communication links will survive, thus providing at-sea submarines with warning and an “execute message” with the same or a higher degree of reliability than expected for ICBMs and bombers — if the latter survive at all! If an “executive” message is released, the SSBN force will receive it. Even in the worst possible case where all surface facilities are destroyed in a preemptive nuclear attack, SSBNs at sea could respond. U.S. and allied naval and merchant ships are routinely located throughout the world’s oceans. These ships can provide high-frequency relay for an “execute” message if one is released by a reconstituted u.s. national leadership and put “on the air” by any means.

In addition to the OHIO-class SSBN being able to execute a full range of strategic options under all conceivable conditions when equipped with the D-5 missile, other fringe benefits occur. For instance, this sea-based system is cost effective in that fifty percent of the U.S.’s total reentry vehicles are carried on SSBNs at a cost of about ten percent of the navy’s budget. Also, because sea-based systems are survivable, they do not require the massive strategic operational and warning organizations needed to provide the ICBM and strategic bomber forces with enough warning to preclude the “use-’em-or-lose-’em” dichotomy. Nor does the SSBN force act as a “lightning rod” for incoming ballistic missile attacks on the continental u.s. In a domestic political sense, the SSBN system has a minimal effect on continental U.S. issues.

Every indicator points to a continuing SSBN system survivability and invulnerability. The D-5 missile is designed for both hard and soft targets with the accuracy and yields necessary to accommodate the widest range of strategic options. The issue of unreliable communications with strategic submarines simply is a non-issue. The redundancy of communication paths throughout the electromagnetic spectrum, along with the multiple options for message relay via friendly ships in port and at sea provides connectivity equal to, and perhaps better than, that available to other Triad systems. Taken in total, the OHIO-class SSBN armed with the D-5 missile is a credible and durable strategic deterrent with significant and survivable deterrent and warfighting capabilities.

Richard T. Ackley, Ph.D.

Naval Submarine League

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