The submarine SLCM, a sea-launched cruise missile, with its unique capabilities presents many diverse problems for arms control negotiators. Because a submarine employs the SLCM, the covertness of the submarine, its ubiquitousness, its high survivability in all levels of connict, its great mobility (particularly when nuclear powered), and its capability to control the tempo of its operations, cause this missile system to have certain military and political capabilities which are considerably greater than for the cruise missile systems used by naval surface and air units.
The problems which the submarine SLCM creates for those trying to impose limitations on its numbers and use are difficult to solve, mainly because of the asymmetries which exist between the two parties involved – the U.S. and the Soviet Union.
The U.S. plans only limited use of the anti-ship version of TOMAHAWK, whereas the Soviets consider the long-range anti-ship cruise missile (with either a conventional or nuclear warhead) of first importance in their major sea strategies -their “first salvo” strategy for initiating a war and their fleetagainst-fleet strategy for gaining control of the seas. For the nuclear land attack mission, the U.S. stresses their nucleartipped TOMAHAWK for deterring the use of enemy nuclear weapons in theater warfare, whereas the Soviets have indicated that their nuclear SLCMs are in effect strategic weapons in the land attack role. Note that there is a geographic asymmetry in strategic targets for nuclear SLCM attacks; the U.S. has the majority of its strategic installations within several hundreds of miles of its coasts, whereas the key Soviet strategic targets are deep inland. Major emphasis by the U.S. is placed on their conventional land attack mission using SLCMs which are being bought in far greater numbers than other versions of TOMAHAWK, while the Soviets have shown no significant cruise missile capability for their conventional land attack mission nor have they written about its application or importance.
Other asymmetries to be appreciated are the few classes of U.S. submarines using TOMAHAWK versus the large numbers of classes of Soviet submarines using long-range SLCMs. As to the capability to change warheads from conventional to nuclear, the U.S. has no means for readily converting their conventional TOMAHAWKS to nuclear-tipped ones whereas the Soviets have indicated a ready interchangeability of warheads. Moreover, all U.S. long-range SLCMs are similar in configuration whereas the Soviets have a wide variety of such submarine-launched cruise missiles as to their sizes and configurations. Additionally, the Soviets tend to use their antiship SLCMs in large salvoes while expecting only a few hits, whereas the U.S. will fire only one or two missiles at a time while expecting single-hit probabilities.
If these asymmetries are properly appreciated, it seems that acceptable solutions to arms control problems may be found.
There are relatively few submarine SLCMs in navies of the world and only the U.S. and the Soviets possess a long-range cruise missile capability in their submarines. The short range U.S. HARPOONs and Soviet SS-N-7s are proliferated to a few additional submarine navies but are seemingly of little concern to arms control negotiators. HARPOON is a turbo-jet driven, sea-skimming, subsonic-speed SLCM which in its submarine version is fired from standard size torpedo tubes and can carry its 507-lb warhead out to about 55 miles. The Soviets’ SS-N7, on the other hand, is fired from dedicated deck tubes and has twice the warhead weight while flying only to about 35 miles. Both are conventional weapons with sufficient standoff range to be a significant threat — like the EXOCET — to surface ships. (The EXOCET, which sank the British destroyer SHEFFIELD in the Falkland Islands war, however, is not classed as a cruise missile, being rocket propelled for its short flight)
The long range submarine SLCMs of the U.S. and USSR — fitted either with conventional or nuclear warheads — must include those cruise missiles with about a 300-mile range in their anti-ship configuration since they have far greater range in the conventional land attack configuration and even greater range when carrying a nuclear warhead. The Soviets’ SS-N12 for example, is identified as having a 300-mile range while carrying a 2200-lb HE warhead at mach 2.5 speed. When fitted with a nuclear warhead its range should far exceed the 300-mile limitation. But even if the weight of the warhead remained the same, this missile, if flown subsonically, could fly to an estimated 1800 miles. Since it is virtually impossible to distinguish between missiles fitted with either conventional or nuclear warheads when they are deployed in a submarine without intrusion into the submarine, and since there appear to be no reliable means for externally verifying the presence of nuclear SLCMs on a submarine, all SLCMs of ranges of about 300 miles must be classed as long-range missiles.
The long-range submarine SLCM for the U.S. is the turbo fan-driven TOMAHAWK. It has four versions all of which closely resemble each other in configuration: a 1550-mile nuclear warhead version for land attack, (the TLAM-N); a 290-mile anti-ship missile with a Bullpup 1000-lb warhead of high explosives, (the TASM); and 800-mile land attack missile with a conventional shaped-charge warhead (the TLAM-C); and a similar-range land attack missile with a dispensing warhead of 166 BLU-97/Bs –shaped charge fragmentation and incendiary bomblets — for attack on enemy air bases, runway cratering, and air defense systems. The land attack TOMAHAWKs have a Terrain Contour Matching (TERCOM) mid-course guidance system with a Digital Scene Matching Correlator (DSMAC) system for terminal homing. TOMAHAWK can be launched from standard torpedo tubes and vertical launch tubes. Ready conversion of TOMAHAWK from a conventional to a nuclear warhead is not considered to be practical at this time.
At least half of the U.S. Navy’s attack submarines are equipped to use TOMAHAWK and about 1500 TOMAHAWKs are in the present stockpile. The planned production of these weapons of all versions is 3,994. To greatly increase the flexibility of TOMAHAWK. use, Collins Radio is designing a navigation system using two GPS satellites to provide continual faxes for mid-course guidance. This missile guidance is practical for virtually all parts of the world and gives highly accurate geographic positioning to the missile — sufficient to make it applicable to Third Power conflicts and against terrorist activities, anywhere.
The Soviet stockpile of SS-N-3s, 12s, and 19s is already well over 3,000 with large numbers of additional missiles being produced including the SS-N-2ts and 24s. The SS-N-21 is thought to be similar to the torpedo tube launched TOMAHAWK but with only a nuclear version. It is being deployed primarily in nuclear submarines but may possibly be used from Soviet conventional submarines as well. Most of the Soviets’ long-range submarine SLCMs are deployed in the 29 ECHO-class boats, with their eight large deck-tube launchers. The ECHOs now carry the SS-N-12 which replaces the SHADDOCK 1.2 mach, 500-mile weapon which in the ’60s and ’70s was believed to have a nuclear land attack capability. This 12-ton, turbo or ramjet cruise missile with a 2200-lb HEor nuclear warhead for the anti-ship mission, flies at mach 2.5 speed to 300 miles. It can surface skim, uses a programmed autopilot with radar altimeter for midcourse cruising and has either IR or radar terminal homing. The SS-N-19 is an improved SS-N-12 and is launched from the 14,000-ton OSCAR’s 24 vertical tubes. The Soviets latest submarine SLCM is the SS-N-24. It is presently being flown from a single YANKEE submarine, and is thought to be a missile for either a new class of submarines or for more YANKEE conversions from their original ballistic missile configuration.
The Anti-ship Long Range SLCM
Long range anti-ship SLCMs of about 300-mile range are of prime importance in the Soviets’ sea strategies but of so little importance to the sea strategies of the U.S. that the TOMAHAWK anti-ship version has been belatedly funded and only 593 such missiles are in the present arsenal — little more than a shipload of four per nuclear submarine. And, whereas the U.S. anti-ship missiles have only conventional HE warheads, many Soviet anti-ship missiles are thought to carry nuclear warheads. A surprise strike against attack carrier forces using only a few nuclear SLCMs would be easy to deploy and would be consistent with the Soviets declared strategy for a “first salvo” initiation of war against the United States. A nuclear SLCM might be the best means for destroying U.S. attack carriers in port areas.
The U.S. sees the anti-ship TOMAHAWK as useful against surface targets of opportunity. At the initiation of hostilities the submarine anti-ship SLCM might be used against valuable enemy ships which are located on the submarine’s peacetime plots of area shipping and warships. It is also possible that in the far-out picket positions for protecting U.S. battle groups, submarines might be directed to take under fire enemy surface ships threatening the U.S. battle groups with their long range cruise missiles. There appears to be no allowance of missiles to be used against Soviet merchant ships and their escorts -even though the Soviets have the second largest merchant fleet in the world.
The USSR, on the other hand, makes the submarine antiship SLCM the prime weapon in its major sea strategies with, secondarily, the land based naval bomber’s anti-ship ALCM as a complementing weapon system. (Since the U.S. has no comparable long range naval air delivery system — the P-3/HARPOON system not having comparable standoff delivery range — the Soviets’ anti-ship ALCMs thus pose additional problems in arms control deliberations.) In both their strategies, the “first salvo” for initiating a major war against the U.S. and the “fleet-against-fleet” strategy in an ongoing sea war, the submarine and air strikes against the major elements of the U.S. surface fleet can be with a relatively few nuclear SLCMs and ALCMs or with a great number of conventional long range cruise missiles delivered from a relatively few dispersed platforms but coordinated to ensure a few critical bursts or hits on their planned targets causing a decisive result from a single massed missile strike. The very large and steadily increasing stockpile of anti-ship cruise missiles — for submarines, at least ten times that of the U.S. — is a good indicator of the relative importance of the anti-ship mission to the Soviets as opposed to the U.S. Significantly, the Soviets’ conventional submarine SLCMs are launched from basically only two classes of submarines, the ECHO and the OSCAR. However, the nuclear anti-ship versions, one of which is launchable from a standard torpedo tube and which is likely to be used from many classes of Soviet submarines, greatly compound the arms control problem relative to nuclear weapons. In this regard, conventional versions of the SS-N-21 — like those of TOMAHAWK — are likely to appear in several additional classes of Soviet submarines.
The Nuclear Land Attack SLCM
Only the U.S. TLAM-N, a nuclear TOMAHAWK of ;~bout 1500-mile range and reportedly with a 200 Kt warhead, seems to meet the requirements for a long range nuclear land attack SLCM and could be subject to follow-on START discussions. With only about 350 of such TOMAHAWKs in the present U.S. inventory, an elimination of all sea-launched nuclear SLCMs would affect no more than a few hundred such submarine weapons. However, this would basically eliminate the effective deterrence of nuclear war due to the theater threat they pose against battlefield and behind the lines objectives which support an enemy’s ground and air warfare.
On the other hand, only the Soviet SS-N-21s and 24s are thought to be long range nuclear land attack SLCMs — with their 1500 to 1850 mile ranges. Several other Soviet cruise missiles in their nuclear versions should exceed the 300-mile lower limit in range but are somehow not being subjected to any consideration as long range missiles. The SS-N-3s, 12s, and 19s, although recognized as having about a 300-mile range when carrying a conventional warhead, should carry a nuclear warhead close to 800 miles due to the decreased weight of the warhead and its reduced volume which can be converted to additional fuel tankage. Since the SS-N-12s and 19s are believed to have interchangeable warheads, the stockpile of nuclear land attack SLCMs can be, again, some ten times greater than U.S. nuclear submarine SLCMs. Significantly, although the accuracy of the Soviet SHADDOCKS in the nuclear land attack mission in the ’70s was considered to be very low, today the newer missiles probably enjoy geographical navigation using a satellite system similar to Navstar for midcourse guidance of missiles while using good inertial guidance as well. The errors in terminal flight should thus be expected to be in the range of tens of meters.
It might appear that, by giving up their nuclear SS-N-21s and 24s in START negotiations, the Soviets could be losing all submarine nuclear cruise missile capability; but this would not be the case. However, eliminating nuclear land attack TOMAHAWKs would sacrifice a major U.S. capability to deter or fight a nuclear war. Thus, the asymmetries between the two navies as to numbers of nuclear warheads assigned to submarine SLCMs and to submarine platforms which employ these weapons, seemingly make START agreements on nuclear SLCMs virtually impossible to consummate. And this might best serve U.S. interests. Importantly, submarine launched nuclear cruise missiles, while achieving attack surprise, can be discreetly timed in their use to produce a maximum political effect. As Max Kampelman, Head of the U.S. INF negotiating team noted, “the nuclear (U.S.) SLCM is a weapon to induce negotiations and a means to impose our will on the enemy.”
The Conventional Land Attack SLCM
The conventional land attack SLCM should “alter many existing tasks performed by manned strike aircraft.” Vice President Dan Quayle also notes in his recent article in the Journal of Defense and Diplomacy, “In some land attack missions, submarines will be critical to enable us (U.S.) to get safely within range of targets such as Backfire bomber bases and key defense complexes — particularly because it may be necessary to attack Soviet naval bases.” He also wrote that, “in the case of Libya, had we had enough conventionally armed land attack cruise missiles of the right range, and with the right targeting information, we might not have needed any manned aircraft.” To these two applications of the conventional land attack SLCM – for a major non-nuclear war and against terrorism — should be added its use in low level conflicts involving third power countries. The evident U.S. emphasis on responding to these types of warfare with SLCMs is shown by the numbers of such TOMAHAWKs which are programmed, about 2650, versus the relatively few anti-ship missiles which have been programmed, only about 600. With an approximate range of 800 miles when configured with either an HE warhead or a warhead of multiple submunitions, the submarine conventional land attack SLCM adds an important new dimension to U.S. SSN operations. Moreover, while the U.S. submarine ASW mission is being reduced in scope because of the quieting of Soviet submarines, the submarine land attack SLCM is growing in importance. Even as a major war with the Soviets becomes increasingly unlikely, the projection of power from submarines is seemingly increasing, using TOMAHAWKs against the shore objectives of lesser countries in crisis situations or against countries harboring terrorist activities. TOMAHAWKs, with a frontal radar cross section “no bigger than a bird” and with a low trajectory in flight, by using TERCOM for mid-course guidance and DSMAC for terminal homing have an undetectability and accuracy that makes them appropriate for such missions. But having TERCOM for all possible trouble spots is such a monumental task as to be the Achilles heel of this type of cruise missile. A satellite navigation system for the SLCM will provide a more practical weapon for such types of warfare.
The Soviets’ long range conventional SLCMs for land attack, on the other hand, are far larger in frontal radar cross section while their warheads are at least double the weight of those used by TOMAHAWK. Moreover, they are easier to track and destroy though flying at far greater speeds and they are believed to have insufficient terminal accuracy to be of much use in the conventional land attack role. It is possible though that their guidance systems have progressed well beyond those observed in the first generation Soviet cruise missiles and that they may have good terminal accuracies.
In effect, the greatest emphasis placed on a U.S. submarine SLCM capability is on the conventional land attack version of TOMAHAWK, whereas there seems to be little evidence that the Soviets have made this an important mission for their cruise missiles.
In summary: the SLCM is fundamentally a new form of air power which is employed in different ways and with a different emphasis on its importance in the naval strategies of the two superpowers.
Although START deliberations to date have indicated a Soviet requirement to address all SLCMs within the arms control regime under negotiation, it would appear to be unreasonable to include any SLCMs in START except possibly the long range nuclear ones. Thus for submarine SLCMs a definition is needed of which submarine~Jaunched long range nuclear cruise missiles should be considered by START negotiators. For the United States, TOMAHAWK is the only nuclear SLCM and it has a maximum range of about 1500 miles. For the Soviets, however, there are five different types of nuclear submarine SLCMs which might be flown to an equivalent or longer range — with three of them recognized as about 300-mile non-nuclear missiles but which fly a much greater distance by taking advantage of the lesser weight of a nuclear warhead and its reduced volume which can be converted to additional fuel tankage. Additionally, these three supersonic speed submarine SLCMs, when flown subsonically, can also have considerably increased ranges. Still, though the prime use of the nuclear submarine long-range SLCM differs between the U.S. and the USSR — land attack for the U.S., anti-ship for the Soviets — a ceiling on total nuclear warheads might be negotiated. But the great need of the U.S. to deter or control the enemy use of theater nuclear weapons and the Soviets’ threat against U.S. carriers which is posed by nuclear SLCMs, make some token number of nuclear submarine SLCMs for both sides reasonable. There is likely to be an insistence upon verification of numbers of deployed nuclear warheads for submarine SLCMs and an equal resistance to intrusion into submarines for verification. Thus, external means of verification are indicated.
For the non-nuclear submarine SLCM, there is little START interest except possibly for the interchangeable warhead issue. But this is resolvable by external observation of submarine weapon loading. Thus, the non-nuclear SLCM arms control issue should be part of separate deliberations. Recognizing that the prime U.S. use of the non-nuclear submarine SLCM is for land attack while for the Soviets it is anti-ship, mutual reductions in these weapons pose an even more difficult problem for arms control negotiators. Submarine anti-ship SLCMs are essential to Soviet sea strategies with land-based bomber ALCMs complementing the submarine’s missile capability. On the other hand, carrier based aircraft are essential to U.S. sea strategies while submarine land attack SLCMs provide the complementing function. Thus, it seems unlikely that there can be agreed upon limitations of non-nuclear submarine SLCMs, though a changed environment of reduced U.S. carrier strength and a similar reduced threat of Soviet reaction to U.S. power projection from the seas in a conventional war, can be cause for suggested reduction in submarine SLCMs for both sides.
Dr. Jon Boyes and W. J. Ruhe