Undersea Global Strike
by Joseph J. Buff, 2006

ARTICLE ORIGINALLY APPEARED AT MILITARY.COM, March 13, 2006

For America’s Submarine Force, both transformational working concepts and innovative deployed capabilities have been multiplying in recent years at a breathtaking pace. Some projects now in the pipeline -- which I’ll cover in my next essay –- include firing supersonic Sidewinder anti-aircraft/anti-ship missiles from a submerged SSN’s existing Tomahawk Vertical Launch System tubes, shooting clutches of conventional theater ballistic missiles out of one of a converted SSGN’s (ex-SSBN’s) former Trident sub-launched nuclear ballistic missile (SLBM) tubes, and launching and retrieving unmanned aerial vehicles (some armed) through the SSGN’s “repurposed” seven foot inner diameter tubes. Today’s discussion will focus on another timely yet controversial notion: rearming some of the latest Trident II D5 missiles with high-explosive warheads and deploying them in a few tubes on Ohio-class SSBNs -– which would continue to serve primarily in their thermonuclear deterrent roles.
An idea will be offered below which might, after further study, fix the biggest problems with fielding non-nuclear (“conventionally”) armed Tridents on an SSBN thus tasked to perform such new double duty. But first, why does this subject even come up, and just what are these problems as noted by critics?

The Pentagon has expressed the compelling need for one or more systems that achieve precision non-nuclear strike missions promptly against “time urgent targets” globally. Here precision means hitting the target with GPS-guided (or equivalent) accuracy, say a maximum miss of ten yards. Prompt means an extremely rapid cycle from receipt of intell on a target’s location to munitions arriving to obliterate said target. (“Prompt” has been formally defined as one hour, so in this context it requires a weapon flight time of barely thirty minutes, even less.) Global means exactly that: the capacity to “reach out and touch someone” –- or some thing –- anywhere on Planet Earth.

Achieving this Prompt Global Strike in practice is a rather tall order. But it’s absolutely necessary, to meet the expanding medley of threats America faces today and tomorrow. For one example, suppose Osama bin Laden is spotted getting a bit of fresh air outside a cave redoubt in the eastern Afghanistan mountains. He’s vulnerable, but not for very long. As another illustration, imagine a ballistic missile is spotted on a North Korean launch pad, busy being fueled before launch -– and the DPRK just fired one high-explosive missile at Japan. This second missile might carry an A-bomb. American and allied forces are exhausted and out of position due to a month-long combined exercise in southern WESTPAC –- so what do you do? Or posit that an advanced diesel sub is sitting at a pier in Iran, about to unload nuclear weapon technology smuggled by the Russia mafia via a covert rendezvous with a “neutral” merchant ship in the Gulf of Oman. That surfaced, stationary sub is a target of opportunity that, in some imaginable scenarios, we’d very much want the option to blast to pieces, before its nefarious cargo could be dispersed and trucked to Iran’s hardened underground bunkers. Every minute would count.

Now comes the issue of implementing Prompt Global Strike truly promptly. This isn’t as easy as it sounds. A Tactical Tomahawk cruise missile is subsonic, flying as fast as a 747, and to reach its maximum range of about 1,500 nautical miles will take more than two hours –- too long. Bombers and fighter-bombers, whether land or sea based, even if supersonic, can take just as long or much longer to penetrate to their objective, even when using stand-off weapons. Prompt Global Strike thus calls for a different approach, one based on intercontinental-range ballistic missiles. Depending on their programmed flight path, these reach speeds approaching Mach 16.

Two competing solutions are being bandied about in the Pentagon, one from the Air Force and one from the Navy. What makes the debate complex is the big fundamental risk behind Prompt Global Strike, whatever form(s) the hardware takes and regardless of which armed forces branch or branches “own” it: An intercontinental-range ballistic missile launched by America against a deserving third party could be mistaken by Russia or China as the start of a nuclear strike against them, inviting immediate retaliation by ballistic missiles armed with H-bombs. When individual warheads have yields of hundreds of kilotons, and one modern ICBM or SLBM can carry several independently targeted warheads (MIRVs), it pays to not take any chances.

Both the Air Force and the Navy, no slouches, have offered solutions to this potentially fatal drawback of Prompt Global Strike. The Air Force suggests building some new ICBM silos on America’s coasts, well away from the nuclear ICBM silos in the Midwest, to reduce ambiguity of intent. The hope is that anyone likely to panic and try to nuke us due to a Prompt Global Strike attack will “realize” that these coastal launch points indicate a conventional warhead is bound for some terrorist or rogue state. This idea, unfortunately, is dependent on Russia and China having precise launch-detection sensors and flawless, utterly rigorous command-and-control –- dangerous assumptions. Open inspection of the conventionally armed coastal ICBMs, and advance notice via Hot Lines to Moscow and Beijing when a Prompt Global Strike against some bad actor is slated to occur, sound great but might not make adequate allowance for Murphy’s Law. And Murphy’s Law rules when the ICBM trajectories would probably pass over Russia or China or both before hitting their targets.

The Navy’s suggestion is to include some Trident II D5s armed with non-nuclear warheads on SSBNs when they go on patrol. This provides our Commander in Chief with the option to use a strategic deterrent nuclear sub for a second purpose: to launch a conventional Prompt Global Strike from a stealthy platform hiding underwater. There are considerable challenges with this approach, however. Reconfiguring an SSBN to be able to fire two types of missiles -– given the maze of hardware, software, safeguards, and radiation protection already required when some of the warheads are nuclear -– could lead to expense and delay. It also requires the same vessel to have two separate logistics, maintenance, and crew training tracks, further making the arrangement sound like a bundle of nasty headaches. If the SSBN is on station in its assigned alert patrol area near Russia or China, there’s the same issue with SLBMs as with ICBMs -- seemingly-nuclear trajectories coming toward countries able to shoot back at America with their own missile nukes. Or, to avoid this geographic conflict, the SSBN could cruise to a better launch point. But that takes considerable time, compromising the “prompt” part. It also takes the whole sub far off station, compromising its nuclear deterrent value, and spoiling its all-important stealth once it launches a single conventional missile.

And there’s another problem which I think naysayers could never be convinced to ignore: If the same SSBN carries two types of missiles, and a conventional Prompt Global Strike order ever does comes through, what stops a worst-case tragic error where the wrong type of missile gets launched? The mistake doesn’t ever have to happen. The mere possibility of it might not go over well in Congressional subcommittee hearings scheduled soon. Plus, Congress has already expressed reluctance over steps that appear to make crossing the threshold to going nuclear any easier or more likely –- a mixed missile load on an SSBN might be seen by some on Capitol Hill as violating that special taboo.

Permit me to offer a possible answer to most of the difficulties involved in undersea-based Prompt Global Strike as detailed above: “Repurpose” a small number of in-commission SSBNs to serve entirely as conventionally-armed Trident II launch platforms. For some background, 18 Ohio-class Trident subs were built. The four oldest are almost done being converted to SSGNs, which because of permanent changes to all their launch tubes and other equipment are entirely unable to shoot any Tridents, regardless of the warhead involved. Discussion has been going on gradually for some time of maybe retiring or repurposing up to four more of the Trident subs still in service as SSBNs. The viewpoint supporting such a move is that, in the current and forseeable strategic environment, a fleet of 10 in-commission SSBNs is sufficient for America’s needs. (A new design of SSBN to replace the Ohio-class as it ages out is currently planned to enter service around 2030.) If those four additional SSBNs did become available for repurposing, one use suggested for them (other than scrapping the lot, which in my mind would be a terrible waste), is to convert them into more commando-and-Tomahawk SSGN vessels. But in the big picture, maybe the existing four SSGNs are enough, and dedicated Undersea Prompt Global Strike is a viable, maybe essential use for any further redundant SSBNs. Consider the advantages of what purely for talking purposes I’ll label an “SSCN” -- an SSBN who’s Trident missiles all have conventional (non-nuclear) warheads.

With Blue and Gold crews alternating at sea, the SSCNs would achieve the same ultra-high availability as current SSBNs and SSGNs. Logistics, training, and safety issues already mentioned for a mixed missile load are nicely resolved. And best of all, so is the problem of ambiguous missile type and trajectory. Borrowing a good idea from the Air Force, of repositioning the launch points, the SSCNs could be ordered into alert patrol areas that are completely out of range for the Trident II D5 against Russia or China, let alone their warheads not overflying either country. This new type of Prompt Global Strike sub could be kept at the ready in far southern latitudes, an idea already proposed by the Navy but to my knowledge only in the context of what opponents consider overly risky dual-use SSBNs –- whose expensive nuclear Tridents would mostly be of scant utility when positioned down toward Antarctica. To get to this SSCN solution, one needs first to abandon the Cold War-era image of ICBMs flinging back and forth across the North Pole. (But a thorough grounding in Cold War theory on nuclear weapons use remains essential.) In undersea-based Prompt Global Strike against terrorists and rogue states, the North Pole has nothing to do with it. And the South Pole, which gets brought up a lot in this context, has even less to do with it.

Data published by the U.S. Naval Institute indicates the maximum range of a Trident II D5 SLBM is 6,000 nautical miles. Much of the trajectory extends through outer space, cleanly resolving the problem of in-atmosphere overflight rights, and the time to target is reportedly only 24 minutes at most –- very prompt. By an extremely useful coincidence, given the size of the earth (about 24,000 miles in circumference), this means that one SSCN can hit anything within a hemisphere centered on the ship’s location. This is not an exact statement, because for brevity I’m leaving out complicated issues of orbital mechanics, but it’s close enough.

Consider that the most likely targets for conventional Prompt Global Strike would be terrorists and rogue states. One SSCN on station in the extreme southern Indian Ocean, far from any shipping lanes (which also solves the problem of launch debris), could hit anywhere in the “terror and piracy belt” extending from North Africa through the Middle East and all the way to the Strait of Malacca and the Indonesian Archipelago. Yet Russia and China would not feel threatened, since if they knew anything at all, they’d know that the missile was coming north from a sub near Antarctica, and it lacked the range to threaten them. All this is because of another useful coincidence: which countries are located where upon our “third rock from the Sun.” (I’ve said this before and I’ll say it again, it really does pay to just look at a globe. Maybe watching too many Powerpoint briefings on flat-screen displays makes people think too much in two dimensions?)

Don’t forget that discussions would be needed with India and Pakistan as well. Although they lack missiles able to reach the U.S. homeland, a Prompt Global Strike launch might be mistaken by each as the start of a nuclear attack by the other, triggering a catastrophic regional A-bomb and H-bomb exchange. But again, the proposed SSCN’s SLBM launch point and direction of flight should quickly assuage such fears. Theater ballistic missiles from India and Pakistan aimed at each other would move west-east and vice versa, not northward from thousands of miles away at sea.

As an alternative, one SSCN far southeast of New Zealand could, among other things, hold North Korea (but not Russia) at risk, and could just barely threaten a slim slice of coastal China immediately opposite Taiwan. Who could ask for more?

Rapid communication of fire-mission orders to the SSCN would not be the problem that some pundits think. No longer part of America’s thermonuclear deterrent triad, an SSCN on patrol could afford to expose itself more than an SSBN to stay in perpetual touch with higher command. That exposure would be minimal anyway, since the sub can constantly trail a floating wire antenna just below the surface. This would serve as a “bell ringer,” to get detailed orders by quickly coming to periscope depth and raising a low-observable high-baud-rate antenna mast for communications via satellite. No more the excruciatingly slow extremely-low-frequency (ELF) method of talking to boomers down deep. (In fact the U.S. Navy’s two huge ELF transmitters, in Michigan, were dismantled as no longer needed, and to save costs.)

Since the supply of converted SLBMs is not intended to be large, any one SSCN can deploy with some of its 24 tubes filled with ballast -- and extra non-perishable food? -- and still be very effective. To satisfy applicable arms-control inspection treaties signed with Russia, Moscow’s observers could examine the warhead bus of the non-nuclear Trident missiles just before they’re loaded into an SSCN outbound on patrol. Ditto for Beijing, if they need reassurance.

Conventional Prompt Global Strike is vital to national defense and homeland security. Implementing it is a job that the Silent Service seems uniquely suited to help achieve, and participation by the Air Force as well may offer more fire-mission options, better tactical flexibility, and needed systems redundancy in a transformational non-nuclear dyad.

The big problem with this is one of our competitors seeing a ballistic missle launch deciding, "Hey, this is for real!"   and launching their own.

A conventionally tipped HE missle or a nuclear MIRV tipped missle are going to look remarkably similar.

Too big an opportunity for mistakes.

Not a bad idea at all.

Quoted: The big problem with this is one of our competitors seeing a ballistic missle launch deciding, "Hey, this is for real!"   and launching their own. A conventionally tipped HE missle or a nuclear MIRV tipped missle are going to look remarkably similar. Too big an opportunity for mistakes.

That's pretty much what the article is talking about.

That's pretty much what the article is talking about.

Yup.  That's all I was saying.  Too much chance for mis-communication....

This happened in 1995 when the world was a quieter place.

Russia's early-warning defense radar detects an unexpected missile launch near Norway, and Russian military command estimates the missile to be only minutes from impact on Moscow. Moments later, Russian President Boris Yeltsin, his defense minister, and his chief of staff were informed of the missile launch. The nuclear command systems switched to combat mode, and the nuclear suitcases carried by Yeltsin and his top commander were activated for the first time in the history of the Soviet-made weapons system. Five minutes after the launch detection, Russian command determined that the missile's impact point would be outside Russia's borders. Three more minutes passed, and Yeltsin was informed that the launching was likely not part of a surprise nuclear strike by Western nuclear submarines. These conclusions came minutes before Yeltsin and his commanders should have ordered a nuclear response based on standard launch on warning protocols. Later, it was revealed that the missile, launched from Spitzbergen, Norway, was actually carrying instruments for scientific measurements. Nine days before, Norway had notified 35 countries, including Russia, of the exact details of the planned launch. The Russian Defense Ministry had received Norway's announcement but had neglected to inform the on-duty personnel at the early-warning center of the imminent launch. The event raised serious concerns about the quality of the former Soviet Union's nuclear systems.

"The Russian Defense Ministry had received Norway's announcement but had neglected to inform the on-duty personnel at the early-warning center of the imminent launch."

That's the point I'm making.   I'm not sure we want to rely on the dubious efficiency of the e-mail of potential adversaries to get the word.

...we can do this, but is it a good idea...