Saturday, August 18, 2012

SSGN - The Navy's Best Strike Platform

I’d like to talk about what I feel is the Navy’s best platform, the guided missile submarine (SSGN).  Their existence is not a secret by any means and yet relatively few people are aware of them or have a good feel for their capabilities.

SSGN - 154 Strike Missiles

There are four SSGNs and they were converted from Ohio class ballistic missile subs.  These are pure Tomahawk land attack missile platforms.  Of the original 24 Trident missile tubes on the Ohio, 22 were converted to hold 7 Tomahawk cruise missiles each, giving a strike capacity of 154 missiles.  The remaining two tubes were converted to swimmer lockout chambers for special ops.

Think about what these SSGNs provide.  A massive land attack capability is contained in a single ship which is the hardest platform to find in the world.  When we discuss ways to overcome the Anti-Access/Area Denial (A2/AD) threat this has got to be the main answer.  An SSGN can penetrate the A2/AD zone with relative ease and deliver an entire surface group’s worth of cruise missiles with near impunity. 

The only drawback is that the Navy has only four of these subs.  While that is plenty during peacetime, the Navy will certainly wish for more if war with China occurs.

VPM with Seven Missiles

The other problem is that the SSGNs are scheduled to be retired starting in about ten years and the Navy has indicated that they will not produce a direct replacement.  The currently discussed solution is the addition of a Virginia Payload Module (VPM) to stretched versions of the Virginia class.  Four modules would be added to each Virginia.  Each module holds 7 missiles which would add 28 missiles to the 12 already present in Virginias for a total of 40 missiles per sub.  Thus, four of the stretched Virginias would provide the same strike capacity as a single SSGN.  The Navy estimates that the conversion would add about 20% ($400M) to the cost of a Virginia.  Bear in mind that Navy cost estimates are notoriously underestimated. 

On the plus side, distributing the strike capacity among four subs instead of one spreads the risk and decreases the impact of losing a single platform.  On the minus side, having to send four subs to do the job of one makes for a crowded launch area and increases the risk of detection.  Whether it’s better to have four strike platforms versus a single one depends on a detailed understanding of submarine operations that I just don’t have.  The Navy built the current SSGNs as a single platform because that’s what they had to work with.  They’re looking at building multiple, smaller platforms now because, again, that’s what they have to work with, at least until the next generation Ohio replacement, the SSBN(X), becomes available. 

The SSGNs are our single most potent and effective strike platform.  While the cost of providing replacements in the form of stretched Virginias is high, this is one area where the cost is fully justified.


  1. I'm of mixed feelings on the SSGNs. Once they fire off their 154 TLAMs, they have to make the long journey back to base to reload.

    Alternatively, we could have spent those billions on the old Boeing proposal for the B747, each carrying 72 cruise missiles. Two B747s could deliver an entire SSGN load of missiles every day or two.

    I like the VPM though. Being able to distribute modest-sized strike packages around the globe undetected is a handy feature, IMHO. Two VPM-equipped Virginias could handle an Op Infinite Reach-sized strike.

  2. B Smitty
    SSGNs are invisible, 747's are not.

    One provides a 0 hour strike, the other follow on hits.
    Use the SSGNs to buckle runways, and then 747s, or conventional strike platforms, to destroy ground aircraft, fuel and munitions ect.

    Without the SSGN strike, your 747s would would be devastated by enemy air power

    I did my best at a UK/Argentina war to demonstrate the concept.

  3. I think SSGN's provide an on call tactical strike. Though I think they should come out with a Tactical trident and convert some Trident silos and some trident D5's to Conventional Prompt Global strike with the capability of using a trident to strike at targets using trident technology.

  4. TrT,

    Agreed. The SSGNs are most valuable for the zero-hour strike. However I wouldn't waste million dollar shots on runways. Stick to key C3 nodes, and hope enough unstealthy TLAMs get through.

    How vulnerable are aircraft that launch missiles from 500+ nm away? If we had built JASSM-XR, it could be even further (~1000nm).

    And we could develop long-ranged AAMs for bombers. How about a load of 72 air-launched SM-6s in one B747 to make a hole for the rest? Flying AEGIS anyone? ;)

    1. Not everyone appreciates the distances involved in the Chinese A2/AD scenario. The zone extends 1000 nm or so out from the mainland. If we want to strike a target that's 500 miles inland, for example, using a 1000 nm Tomahawk (neglecting non-linear waypoints which would reduce the effective range), the launch platform has to close within 500 nm of the mainland - well inside the zone. Perhaps this is the purpose behind the Chinese desire to build carriers? Carriers with fighters that would be able to stake out the 500 to 1000 nm area and pick off strike platforms like the 747 or any other non-stealthy, unescorted platform? Just thinking out loud.

    2. Agreed, the distances are large here, however I still think the B747 has some advantages.

      An SSGN's only defense is stealth. The act of firing 150+ missile results in a long "indiscretion period" that could be picked up and tracked by MPA. If this happens, its only recourse is to evade at 20-30kts. This could result in a lengthy cat-and-mouse game with multiple MPAs, especially if the SSGN had to get close to shore to fire.

      A B747 at least can leave the area at 500+kts.

      A Chinese carrier would just be another target for a flight of B747s, assuming a suitable AShM existed (LRASM-A?).

  5. I can see the appeal of having a single SSGN carrying 154 TLAMs but I also see the usefulness of spreading Tomahawk capability across the SSN force.

    The actual cost of the module should be close to estimates. It is a straight-forward plug into an existing, mature design. Even the Navy would have a hard time screwing that up. But not impossible.

    A concern I would have is arms-control related. Would the VPM create problems for START? Large diameter hatches and silos could make the Russians think it is a mini-boomer.

    On a submarine side-note, I understand the Navy is going to repair the USS Miami. Might they rebuild it to something besides a basic Los Angeles SSN? A special mission sub?


    1. "Even the Navy would have a hard time screwing that up. But not impossible."

      I got a good chuckle out of that! Well said. Of course, you'd think an organization that has built ships for a couple of hundred years wouldn't miss on the LCS cost estimate by 300% and yet they did!

      Turning a bit more serious, you make two great points.

      One. Does VPM conflict with START? I have no idea. The current SSGNs have essentially the identical modules and that doesn't seem to be causing any concerns. I'll have to dig a bit and see if I can find anything specific. Great question!

      Two. Miami rebuilt as something special? I've heard the possibility discussed that Miami may not be certified (or safe) for deep dives in the SSN role due to heat deformation of the structure. Possibly the sub could be put to a less strenuous use in some sort of special mission role as you suggest. Maybe an unmanned, undersea vehicle (UUV) platform test bed and/or mothership?? Another great question!

      A ComNavOps salute to you, sir!

  6. The reason I ask about the VPM and START is that I believe the Ohio SSGNs have the 7-shot TLAM launcher welded in to satisfy START. From what I have read online the VPM would be flexible enough to take Tomahawk or something else. Would the Russians object to that?

    The START issues are why I think we'll never see a conventional Trident missile under Prompt Global Strike. Other countries will not be able to tell the difference between nuclear and conventional missiles when they are launched. And I would hate to see the Russians or Chinese make their own PGS.

    Wireguided Marine

    1. This is an area I don't know much about. The Chinese apparently have intermediate range ballistic missiles (IRBMs) for use in the A2/AD scenario. How will we know whether they're conventional or nuclear when launched? I know you can eventually determine the trajectory and estimate where it will land which would suggest whether it's nuclear. I'd hate to think that we'll unilaterally limit ourselves from using conventional IRBMs while the Chinese are free to do so. Or have I misunderstood the issue? Any thoughts on this? I appreciate you taking the time to educate me a bit on this!

    2. I believe the VPM tubes are too short for Trident.

    3. Our enemies are already fielding IRBMs, it seems insane for people to freak out about U.S. conventionally tipped ballistic missiles.

      Perhaps if the PRC, NK, and Iran stopped threatening their neighbors, we would not need to IRBMs...


  7. SSGN strike capability is pretty darn good. Targeting capability -- not so much.

    1. You're quite right. Over-the-horizon (OTH) targeting is a challenge, to say the least. We haven't solved it and it's undoubtedly safe to say the Chinese haven't either which is why the "carrier-killer" ballistic missile threat is way overblown.

      As far as our own SSGN strike capability, remember that many (most?) of the higher value targets which would warrant Tomahawk attack are fixed sites like airbases, industrial complexes, and so forth whose location is exactly known. Targeting becomes a simple GPS exercise in those cases.

    2. Assumes you have a working GPS. Availability of precise navigation and timing could be a real problem in an A2/AD scenario.

  8. What is a concern with PGS is that the detection of a ICBM launch could lead to bad decisions in Moscow and Washington. Right after launch the target is difficult to determine. Missile velocity, acceleration, and trajectory have to be tracked a finite amount to predict the impact point. Even with a good BMEWS it can take tens of seconds to narrow the endpoint down to a country.

    Remember the science rocket launched by Norway 17 years ago and Boris Yeltsin? The Kremlin said it was a SLBM launch on Moscow and recommended a counter strike. Luckily, he didn't do it.

    An IRBM launch on the coast of China would not freak out Russia or America.

    The CO of a CSG might get nervous. An ASBM could have a nuke warhead. But so could any incoming Chinese cruise missile.


  9. Nuclear submarines are at a disadvantage in littoral waters. A nuclear reactor emits radiation that heats its surrounding, including water outside the hull of the submarine. Below a certain depth the heated water around the submarine is not visible, as water quickly absorbs over short distance long wave length radiation such as IR (that's why it is possible to communicate with deep underwater sources using very short wavelength up to X-ray). Above that depth aerial and space observation can make out the heated spot of water due to a powerful nuclear reactor.
    For this reason, nuclear submarines are at a disadvantage in waters with shallow depths such as the littorals. They have to stay deep enough to avoid easy detection by their heat emission. That's why a conventional powered guided missile submarine would be better suited to littoral combat.
    Furthermore, the deep depth requirement for nuclear submarines under threat of aerial observation limits their ability to use water above the thermic layer that reflects acoustics (including sonar) above or below. Thus the combination of SSK with communication to an UAV forces a nuclear submarine below the thermic layer, the more shallow that layer is, while the SSK has an advantage by being able to operate above and below the thermic layer.
    Submarines mostly run at very slow speed in order to limit their sound emission. 5-6 knots submarine speed, 12-15 knots convoy speed and 30 knots only for very loud transits such as evading incoming torpedoes. Modern AIP submarines can run at 30 knorts for hours, at 12-15 knots for days and at 5-6 knots for weeks. That leaves them just at a slight disadvatange as fleet escorts, but within a defined area of operation not far from a base or other supply systems, they deliver the same capability for a fraction of the costs due to lack of requirement for nuclear hardening of electronics and construction materials. That SSN so far were supreme to SSK has a lot to do with size and investments into the system. SSK are usually the size of a missile boat to a small corvette, while SSN are from frigate to destroyer size. That makes it pretty evident who pakes more sensors and capable operators. Increasing the size of SSK would further enhance their underwater AIP endurance charateristics and close the existing perceived capability gap to nuclear systems. Thus a littoral combat guided missile submarine should carry Ohio-class firepower in a corresponding size. Such an augmentation would rather eliminate all combat criticism of the LCS as a networked warfare system.


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