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.