A month ago, the nuclear submarine USS Ohio, formerly a highly survivable Trident ballistic missile thermonuclear deterrent platform (SSBN), triumphantly completed the initial sea trials of her conversion to an “SSGN” configuration: a super-stealthy and long-endurance undersea vessel designed for forward presence and deployment of up to 154 Tomahawk cruise missiles, large unmanned undersea vehicles (UUVs), and as many as 100 Navy SEALs or other commandos with their equipment and mini transport vehicles. That's right, the 24 seven-foot-inner-diameter vertical launch missile tubes from Ohio's prior successful career as a “boomer” have all been repurposed.

As the first of four such conversions now in progress at various shipyards around the U.S. (the others subs are Michigan, Florida, and Georgia), Ohio's available payload weight and space -- for counter-insurgency campaigns and conventional major combat (as well as non-nuclear deterrence) -- are unprecedented in America's Silent Service history. And the SSGN's stealth as a big-time Tomahawk shooter is very important. Experience has shown that U.S. Navy surface units operating in confined littoral waters can be shadowed by “civilian” fishing boats or tramp steamers, which report cruise missile launch times and base courses to the enemy homeland via radio. The key element of surprise in the precision airborne strike is thereby lost. An SSGN, in contrast, can sneak to an area well clear of overly-curious opposition eyes before opening fire. The importance of this tactical/strategic advantage cannot be overstated.

The SSBN-to-SSGN conversion concept, as a funded Navy program, goes back several years. Much has been written about it in the open literature. I'd like to suggest three additional possible payload uses for some of the ex-SSBN missile tubes, which I have not seen mentioned elsewhere, to show how extremely flexible and adaptable these new warships truly are.

First, some background. The Ohio-class subs, of which a total of 18 were built (and are still in commission), were intended to “hide with pride,” never detected but always vigilant in case the unthinkable happened and they were ordered to launch their long-range ballistic missiles tipped with multiple hydrogen bombs. As a result, their torpedo rooms were made relatively small, with four tubes like the Los Angeles-class but room for only some 12 of the standard ADCAP Mark 48 torpedoes or Mark 30 torpedo-sized decoys. This made sense when the ship's mission, in an anti-submarine context, was purely defensive. But if an Ohio had launched all her Trident C-4 or D-5 missiles, she could then switch to the offensive, acting as an ersatz fast-attack SSN, hunting and engaging hostile SSNs and SSBNs.

The problem nowadays is that torpedoes do remain a primary offensive and defensive weapon of all submarines, but the modern standard (Seawolf-class, Virginia-class, Royal Navy Astute-class) is a torpedo room with a torpedo carrying capacity three or four times that of any Ohio. Even the Cold War-era Los Angeles design allows space for about twice as many “fish” as do the Trident SSBNs. This weapon capacity matters in any prolonged operation, whether it be deterrence, or anti-shipping, or sub-versus-sub. (Just as two for-instances, note that Al Qaeda alone controls about 20 merchant ships worldwide, and already hundreds of modern diesel subs serve in the navies of countries antagonistic to America.)

On the other hand, the new SSGNs have such a large capacity for Tomahawk cruise missiles because each former Trident tube has been fitted with a sleeve that can hold seven Tomahawks. But a Mark 48 is almost identical in size to a Tomahawk: within a few millimeters of 21 inches in diameter and 21 feet long. By now you probably see where I'm going with this. It might become possible for an SSGN to carry in some of her big missile tubes an additional seven torpedoes each -- launched straight up before they level off for the underwater attack on chosen targets. The use of torpedo guidance wires in this context would certainly be tricky. If the engineering and tactical issues could be resolved, then the ultra-quiet SSGNs would be capable of a very high-intensity anti-shipping and ASW mission, without the need to return often to a tender or friendly port for re-ammunitioning.

The need for eventual re-ammunitioning leads straight to another suggestion: The U.S. Navy has only two submarine tenders still in commmission (USS Emory S. Land and USS Frank Cable), plus two others laid up in reserve, yet the 21st century submarine force has duties that cover the globe. And sad experience has shown that friendly ports near a conflict zone may suddenly become closed to American warships just when those ports are most needed, as international tensions heighten and putative allies realign.

Yet for any submarine to stay maximially effective during a crisis, it needs to spend as much time as possible on active patrol -- and as little time as possible transiting to and from a distant facility where it can replenish unharassed by foreign government objections or by threats of terrorist assault.

One possible answer to help solve this problem would be to install a loading crane inside one of an SSGN's vertical tubes. That would permit the vessel to replenish opportunistically, at a random unimproved forward location. All that would be required would be any stable structure (a pier or moored cargo ship, or even an oil rig) against which to tie up after surfacing and raising the crane, to transfer weapons and cargo. Sub tenders have two types of crane: 5-ton capacity and 30-ton capacity. Since individual cruise missiles and torpedoes weigh under two tons apiece, the smaller type of crane would suffice to reload weapons one by one into empty slots in the vertical tube sleeves. The fresh weapons could even be brought to a clandestine rendezvous in the back of a robust truck disguised to look decrepit. The SSGN breaks stealth for only so long as the replenishment evolution actually requires. Beginning with surprise, and protected by other U.S. Armed Forces' in-theater assets, the SSGN could pop up almost anywhere that's held in American or friendly hands during combat, provided only that the water is deep enough to accomodate her draft.

And how about a return to the days of submarines with deck guns? A new type of main gun is being developed for the next-generation DD(X) destroyer. This 155-millimeter Advanced Gun System (AGS) has a high rate of fire of rocket-assisted GPS-guided munitions that begin their trajectory going nearly straight up, but then arc into a more typical artillery near-paraboloid path. The AGS itself had a low radar cross-section, and its shells have a maximum range of 100 nautical miles. Conceivably, the AGS and accompanying ammo magazine might be adapted into a version that fits within one of an SSGN's payload tubes. This would allow the SSGN to return the favor of protecting other friendly assets, projecting additional multivalent firepower onshore, at sea, or into the air -- and protecting herself during excursions to the surface.

These purely paper notions (which admittedly could be very expensive to implement in practice, and would cause some incremental tactical risks) appear to add whole new dimensions to the envelope of peacekeeping and warfighting uses of the new SSGNs. Both the availability and the flexibility of the basic vessels would be greatly enhanced. Such thinking argues strongly that the four additional Ohio-class SSBNs being considered for...