The U.S. nuclear submarine community has proposed an innovative and potentially highly effective role for the quartet of Trident ballistic-missile submarines being retired beginning in 2002—offensive strike.
Completed from 1981 to 1984, the first submarines of the Ohio (SSBN-726) class will be some 20 years old when decommissioned, i.e., just one-half of their predicted service lives. But the geopolitical environment has changed, and various U.S. defense reviews have recommended retiring these boats rather than refueling them. With their demise, the Navy still will have 14 Trident SSBNs carrying a total of 336 ballistic missiles—96 with eight W76 (100-kiloton) and 240 with eight W88 (450-kiloton) warheads—a force sufficient to meet current national-security requirements.
In their new guise, the four ex-Trident subs would be designated guided-missile submarines (SSGNs). They would be refueled, updated, and converted to carry up to 154 Tomahawk land-attack missiles (TLAMs) or a lesser number of missiles plus 66 special operations forces (SOF) and their equipment. For short periods temporary bunks could be added to accommodate up to 102 SOF personnel.
For the special operations role, each submarine would be modified to accommodate two dry-deck shelters for use by SEALs or other special forces and their "wet" swimmer delivery vehicles, or two of the now-building advanced SEAL delivery systems (ASDS), essentially minisubs to carry "dry" swimmers. Two to four Trident missile tubes would be modified to carry troop equipment, including rafts, and two tubes would be converted to lock-out chambers. This could reduce the Tomahawk battery to 126 missiles (carried in the remaining 18 modified Trident tubes).
Another possibility, put forth recently by Rear Admiral John F. Shipway, director of Strategic Systems Programs, is to reconfigure the C-4 Trident missiles that are being retired for ballistic missile intercept, should the United States pursue a national missile defense program. Pointing to the efficacy of the C-4 in terms of availability, payload, performance, and reliability, Admiral Shipway suggested that the proposed SSGNs were potential candidates for the missile defense role.
At this writing, the SSGN proposal has not been incorporated into Navy program planning for the next few years. Among the myriad issues being raised about its feasibility are:
Cruise missile carriers. The U.S. geographic commanders-in-chief (CinCs)—Atlantic, Pacific, Central, and Europe (including the Eastern Atlantic and Mediterranean)—need a specific number of TLAMs to be available on ships in their areas. The 154 missiles on a Trident SSGN could meet most of a CinC's requirements, but such a deployment would create many questions.
For example: today, a loadout of 154 TLAMs would be carried in perhaps three or four cruisers and destroyers. Those surface warships carry out many tasks beyond land attack: antiair warfare, antisurface warfare, patrol and interdiction, fire support, etc. Would a CinC be willing to give up those ships or would he want the SSGNs in addition?
With only four SSGNs, it would be impossible to keep one available in each CinC's area on a continuous basis. Deployments of six months are about the longest possible with the existing personnel situation. Would relief crews be flown out to the submarines in forward areas, as was done for many years with Polaris and Poseidon submarines? If yes, that would more than double the crew requirements. And what would happen to missile availability when the SSGNs had to return to U.S. territory for major maintenance and overhaul?
In addition, the land-attack mission often requires a high volume of communications and data-link traffic. This will be especially true with the planned tactical Tomahawk, a quick-reaction missile. Could an SSGN maintain its clandestine posture and still handle the communications requirement? When a TLAM is launched, efforts are made to avoid both friendly and enemy ships and perhaps certain geographic areas on the first "leg" of the missile's flight. Data for this flight profile are fed into the missile shortly before launch, based on the launch ship's radar/electronic intercept data as well as intelligence from external sources. Again, would a cruise-missile submarine be able to meet this requirement in all situations?
Special operations transports. Today, SOF are carried in several attack submarines, with seven boats of the Los Angeles (SSN-688) class being converted to carry either a single dry-deck shelter or single ASDS: the Los Angeles, Philadelphia (SSN-690), Dallas (SSN-700), La Jolla (SSN-701), Buffalo (SSN-715), Charlotte (SSN-766), and Greeneville (SSN-772). In addition, the now-building Jimmy Carter (SSN-23) and the planned Virginia (SSN-774) class also will be capable of embarking a dry-deck shelter or ASDS. The later submarines will have "convertible" torpedo rooms designed for rapid conversion to support SOF personnel and enlarged lock-out hatches and storage space for their equipment.
The Navy also has one specialized SOF transport submarine in commission, the ex-Polaris submarine Kamehameha (now SSN-642). That submarine is configured to carry 65 troops. However, the Kamehameha is scheduled to be taken out of service in October 2001, after which she will be stricken.
Thus, there will be a large number of SSNs available to support SOF operations without the Trident SSGN conversions. Indeed, some submarine officers believe that the attack submarines—despite their smaller capacity—will be far more effective:
- There will be more SSNs, permitting greater geographical coverage.
- The SSGNs normally would accommodate 66 SOF personnel, but most operations require smaller numbers of people, from a few to perhaps a score, to be put ashore or taken off.
- It will be easier to maneuver and "hide" an SSN than a Trident-size submarine of almost 17,000 tons displacement, more than twice that of a Los Angeles-class SSN.
Operating in both roles. There is concern by some Navy planners over whether the SSGNs, while carrying SEAL teams or other special operations forces, would be able to perform simultaneously as a cruise missile platform. The submarine might have to leave the assigned missile launch box or area required by the CinC to carry out the SOF assignment, and vice versa.
Also, when operating in the special operations role, the submarine must be clandestine. That may not be possible when communicating (as needed to update TLAM targets and confirm readiness) and when launching scores of missiles.
The SSGN's most important attributes appear to be its clandestine operating mode, high sustained submerged speed, and large missile battery. However, even these features are being questioned. For example, a review of the several TLAM strikes beginning with the Gulf War (1991) indicates that in most if not all situations, clandestine operation of the shooters was not a significant factor. The one potential scenario that has been put forward on an unclassified basis is for a large TLAM strike against enemy air defenses in preparation for a large (surprise) air attack.
With respect to high sustained speed, the Ohio-class submarines have a maximum submerged speed of some 25 knots. Submarines in transit are less susceptible to weather and sea state than are surface ships, but the Aegis missile cruisers Gettysburg (CG-64) and Vella Gulf (CG-72) both crossed the Atlantic recently at speeds in excess of 30 knots. Had the cruisers encountered rough seas, however, a submarine in transit would have had the advantage.
Finally, if surface ships also are to be provided with TLAMs, the potential cost of arming the four large SSGN missile batteries becomes a factor. Each SSGN would carry up to 154 missiles; with test and training launches, more than 700 additional TLAMs would have to be procured—a cost not included in the SSGN proposal (nor are weapon costs included in other warship and aircraft procurements).
The Navy began Allied Force with some 2,300 TLAMs, and unofficial estimates place the number of missiles fired during the Serbian operation at just under 200. Large procurements of replacement TLAMs and tactical Tomahawk production are in the offing, but even an inventory of, for example, 3,000 missiles would provide 12 TLAMs for each of 25 attack submarine with vertical-launch tubes, 61 for each of 26 destroyers of the Spruance (DD-963) class, and about 20 for each of 55 other surface combatants, plus a few missiles for test and training. Under this loadout the Navy's other 25 SSNs with vertical launch tubes would not have any Tomahawks embarked.
Thus, buying 700 more TLAMs for the guided-missile submarines requires a considerable additional investment.
Costs for the four SSGN conversions have been estimated at $5.87 billion:
These include modifying the Trident missile tubes as discussed above; however, some DoD officials believe that on the basis of arms-control agreements, the Navy should cut out the Trident missile compartments and replace them with built-for-the-- purpose midsections. This would add at least $2 billion to the program.
Still, the SSGN concept holds considerable promise for a versatile and effective warship. Planning for the Trident conversions should be initiated, but critical analysis also should be undertaken in terms of both total cruise missile platform requirements and other potential submarine alternatives. In particular, the Navy should consider Los Angeles-class submarines that otherwise would be stricken long before the ends of their planned service lives for conversion—separately—for the SSGN and SOF transport roles.
The cruise missile—both air- and sea-launched—increasingly is the weapon of choice for U.S. military action. The Navy must consider carefully how it best can provide its share of those weapons.