By Joe Buff, MS, FSA
Should the U.S. add land-based mobile ICBMs to its Nuclear Deterrence Triad, or use them instead of fixed-silo nukes? The short answer is no. Such weapon systems were considered during the First Cold War, as one way to make American ICBMs more survivable — by moving them around unpredictably. By jinking hither and yon on random paths while going top speed, they could even seek to outfox inbound enemy warheads. How? The half-hour flight time it would take Moscow to drop a big warhead on a specific location would give the mobile missile-carrier’s crew time to drive out of the mission-kill circle of the ensuing megaton blast.
This mobile basing option made sense to look at closely, once, when Soviet ICBM warheads first became powerful enough and accurate enough to hold our ultra-hardened deep silos at risk. ICBMs mounted on vehicles (road mobile) or concealed in special rail cars (rail mobile) were both studied, but then rejected in the U.S. for a variety of good reasons.
The old, tired idea was brought up again at the March 6, 2019 hearing on nuclear posture of the House Armed Services Committee. [http://bit.ly/2UsfnBw] Mobile ICBMs were suggested at that hearing as a way to supposedly make America’s ICBMs less “vulnerable.” This thought came from certain folks who don’t fully understand the full spectrum of basing options use for and the many different roles played by our strategic deterrent nuclear missile forces as a whole.
Mathematicians and fire-control technicians understand it just takes some simple arithmetic, and a great abundance of your own warheads, to launch a whole salvo distributed in a miles-across pattern that no mobile launcher can ever outrun. This is why, to do mobile basing at all, you’d need a way-big army of these special vehicles. Before you know it, both sides are in another dangerous and wasteful warhead-count arms race.
Enemy MARVing — making each nuke’s reentry vehicle be smart-guided and maneuverable — of the sort Russia and China are working to employ — could “chase down” an evading mobile launcher on an individual basis. No, nowadays, mobile is no panacea.
What’s so very all-right about our fixed-silo ICBM force?
America’s ICBMs are so well dispersed (across several states) and so numerous (about 500) that any sudden superpower-enemy preemptive strike, to make a dent at all let alone take them all out, would have to be so massive that it would face insurmountable technical obstacles to the sheer simultaneity, of all the end-to-end flight paths, needed for real surprise. Allying this with the facts that enemy ICBMs have somewhat less than 100% reliability and accuracy, that a Cold War rule of thumb is that at least two are needed to kill one silo, and that the notorious “fratricide effect” of a large strike would kill some of its own missiles not our silos, one thing is 100% certain: Some of our ICBMs would survive to wreak a vengeance of truly Biblical proportions on that enemy.
But wait, there’s more! Since no enemy would dare start a nuclear war against us without trying to eliminate those ICBMs at the outset, they serve several other very important functions at no additional cost to taxpayers. They are an essential strategic tripwire. The enemy nuclear attack against them — once the first actual mushroom cloud detonations are verified via ground truth on our soil — would mobilize our nation to an immediate proportional nuclear counter-strike. This nuclear counter-strike would be absolutely justified both legally and morally. It would also be absolutely necessary to restore geopolitical equilibrium to a badly disrupted humanity, prevent copy-cats then or down the timeline, protect good world order and global democracy, and force peace restoration on acceptable political terms.
Our ICBMs, despite their alleged vulnerability, and in a real way simply because of this tempting exposure, act as a crucial “roach motel” for enemy nukes, nukes that could otherwise be used against our SSBNs out at sea on deterrent patrol. How? With enough nuclear warheads available for concentrated use, an enemy can saturate very large tracts of the ocean to try for mission kills against our few deployed, super-stealthy SSBNs — without needing to know more than very vaguely where they are. Worse, if a belligerent (and very foolhardy) enemy didn’t have to take account of all our ICBMs in their risk/reward calculations, they could use their strategic warheads against American and allied cities. Whether the warheads were “used” for nuclear attack or nuclear blackmail would hardly be the point. Freedom would die in abject surrender to triumphant, everlasting tyranny.
Our nuclear Triad, by fielding assets that are deployed in very different environments (land, sea, air) and by transiting to their assigned deterrence targets at all different altitudes, provide the ultimate in diversification and interlocking, mutual support. By thus increasing the overall reliability/surety of the whole organic Triad system, they strongly support our national goals for expense savings and for us being world leaders in nuclear arms control and nonproliferation. If we did ever give up our ICBM leg of the triad, we would need a lot more SSBNs and strategic bombers. These would cost much more to build that silos do. Worse, we would need a lot more nuclear warheads deployed to achieve the same ultimate level of survivability for our all-important, decisively deterring second strike. Having more nukes required to be deployed than if we had three Triad legs, due to this lack of diversification, would also be an aid to nuclear terrorists, giving than more nukes to try to steal.
Lastly, to say that the vulnerability of our ICBM force means that POTUS would feel insurmountable pressure to shoot them all off, early in a crisis or even based on a whim of preemption, is so insulting (vulgar) as to hardly merit serious attention. But just for completeness, here’s a quick rebuttal anyway: Our Commander-in-Chief and his top military and statecraft advisers appreciate full well the untouchable survivability of our SSBN force, when deployed in the necessary numbers (12, not fewer) and properly supported by our other forces (including the U.S. Submarine Force’s extremely capable fast-attack escort and combat subs, our SSNs). Our national command authorities most certainly do not view the ICBM force in some vaulted isolation, as precious playthings to “use or lose” at the first sniff of trouble!
What’s so very all-wrong for us with any land-mobile ICBM basing?
Valid concerns about mobile ICBM deployments include first, their security, since the nuclear warheads would be moved around the country on roads and railroads open to enemy espionage, sabotage, hijacking, and theft. A second concern is safety, as motor vehicle crashes and railroad accidents could expose the citizenry to severe radiation hazards. The third worry is civilian survivability, since if mobile ICBM launchers roam the countryside, they might draw nuclear fire down closer onto the citizenry’s vulnerable heads. The U.S. public’s awareness — and undoubtedly, their very vocal objections — would be heightened to safety worries due to the dramatic media coverage of recurrent flaming derailments of oil-tanker trains, and some terrible train versus motor vehicle grade-crossing accidents.
Russia and China do deploy such land-mobile ICBM systems, but these are closed societies compared to America. Importantly, these autocratic states can count on inherently strong internal security for their mobile nuclear deployments, while public safety concerns can be ignored or suppressed. Any protesters can be rounded up and silenced. Perhaps Russia and China have resorted to land-mobile ICBMs because, despite some recent advances, they remain dissatisfied with the robustness of their SSBN capabilities compared to the U.S. and NATO. (France and the UK do not supplement their existing nuclear deterrents, which do include SSBN fleets, with any mobile land-based ICBMs.) The two superpower dictatorships might also be concerned about another way their technology lags behind America’s: Their ICBM guidance and targeting accuracy aren’t as good as ours. This would cost them an important form of parity in any saber-rattling blackmail standoff, let alone (God forbid!) in any actual nuclear exchange.
MIRVing land-mobile ICBMs (several separate warheads on one missile), as Russia and China do but the U.S. doesn’t, makes them a very tempting target for an aggressive nuclear first strike. This is because, if an adversary ICBM is MIRVed (known to carry, say, N nuclear warheads, where N is greater than one), it pays for the U.S. and our allies to invest at least N of our own deterrent warheads in trying to knock out that ICBM — even if we need to use N of our own ICBMs because ours are not MIRVed. That is, the calculus of trade-offs of friendly and enemy warheads is drastically changed by the enemy’s mobile launcher MIRVing. If N warheads are available to our side against one adversary mobile launcher, we can target the general area of a known or suspected ICBM vehicle or railcar as mentioned above, in the hopes that the combined very powerful warhead effects of heat, blast, radiation, and electromagnetic pulses will destroy or at least disable the ICBM and/or its control and launch equipment and crew. A big barrage of nukes in the suspected general area of an enemy mobile launcher does not need good targeting data to have a shot at, at least, some mission-kill damage against that launcher. Mobile ICBM launchers invite profligate expenditure of nuclear ordnance once nuclear battle is joined at all. They are inherently pro-escalatory, and therefore are seriously destabilizing.
Road-mobile launcher vehicles and special rail cars alike, because of their practical weight limitations, are by nature not very hardened. They are a lot more vulnerable to nuclear attack than an ICBM buried in a hardened silo, where it and its crew are protected by thousands of tons of reinforced concrete and shock-absorbing buffer systems. If a land-mobile ICBM system’s stealth were ever compromised, via espionage and/or improved surveillance technologies, they would make a preemptive first strike be awfully tempting to a paranoid-enough defender. They don’t belong in America’s arsenal nor in anyone else’s either.