The “Utility” of Low-Yield Nuclear Weapons

The B61 family of modifications

The B61 family of modifications

An article in the New York Times made the rounds last week, asserting that the new modification (“mod”) of the B61 nuclear gravity bomb was of a lower yield than its predecessors, and arguing that lower-yield, precision weapons are destabilizing to nuclear strategy and that their relatively limited destructive capabilities in turn render them more likely to be used than the multi-megaton, Cold War-era city-busters. It was also proclaimed that this was the death knell for the Obama Administration’s disarmament and arms control efforts, and represented a “new arms race” between nuclear powers.

The argument is well-intentioned, but misguided.

The article quotes the usual suspects – James Cartwright, Andrew Weber, William Perry – and offers some assertions that are patently false on their face.

David Sanger and William Broad, the authors of this piece, focus solely on US weapons development and policy in a bubble, ignoring the larger context of the world in which nuclear weapons exist. As they and their interview subjects characterize it, the United States is the one upsetting the nuclear balance:

Already there are hints of a new arms race. Russia called the B61 tests “irresponsible” and “openly provocative.” China is said to be especially worried about plans for a nuclear-tipped cruise missile. And North Korea last week defended its pursuit of a hydrogen bomb by describing the “ever-growing nuclear threat” from the United States.

This, of course, ignores the fact that Russia has violated the Intermediate Nuclear Forces Treaty, China has refused to enter into any arms control arrangements and is busy expanding its own arsenal (including the production of new nuclear warheads and delivery vehicles; the former something that the United States still will not do), and North Korea has rejected carrot and stick approaches alike dating back several decades. If the Presidential Nuclear Initiatives in the aftermath of the Cold War – or the past 30 years of sanctions – were insufficient to dissuade Pyongyang from nuclear proliferation, it’s hard to envision what would.

But speaking of deterrence, this is where the critics of a more accurate nuclear-armed cruise missile lose the plot. One particularly historically ignorant fear comes from FAS in the Times  piece, who insist that “high accuracy and low destructive settings meant military commanders might press to use the bomb in an attack, knowing the radioactive fallout and collateral damage would be limited.” Is this really an unprecedented state of affairs? Truman and Ridgeway might disagree. The United States is no stranger to its military commanders requesting permission to use nuclear weapons, nor does it lack experience with rebuffing those efforts.

Perhaps more important are the tactical and operational military implications raised by escalation to a nuclear exchange. As Alex Wellerstein ably points out, the nuclear taboo is not solely a moral concern but also a practical one. The benefits and attributes of a low-yield nuclear weapon would make one particularly attractive for use against a US military formation:

Since World War II, the US has the strongest interest in not breaking the “nuclear taboo” because once nukes start becoming normalized, the US usually stands to lose the most, or at least a lot. Massed troops, heavy armor, and fixed bases? That’s how we prefer to fight wars. Massive urban cities conveniently located on coasts? Check. Economy highly reliant on communications, transportation, and other infrastructure? Yeah. Which is probably one of the deep reasons that the US, for all of its lack of willingness to commit to a no-first use policy, has always managed to find a way so far to avoid using the tens of thousands of nuclear weapons it produced in the years since Hiroshima and Nagasaki.

There’s little reason to believe that fielding addition low-yield nuclear weapons of our own would in any way shift this calculus, nor make us in any practical sense more likely to use one of them. Bill Perry and Andy Weber both argue that “because the missile comes in nuclear and non-nuclear varieties, a foe under attack might assume the worst and overreact, initiating nuclear war.” Which, again, ignores 60 years of nuclear age strategy and use doctrine. The United States already has a dual-use air-launched cruise missile: the AGM-86, more commonly known as the ALCM, and which exists in both nuclear (“B”) as well as conventional (“C/D”) variants. For many years, US attack submarines were armed with the dual-use (and now solely conventional) Tomahawk cruise missile. A new cruise missile is hardly a game-changer.

Even if critics are taken at face value – and that a low-yield cruise missile is somehow “more likely” to be used than the existing nuclear cruise missile – they assume that this is a negative development. But on the contrary, the heart of deterrence theory lies in an actor’s willingness to retaliate – this is what deters. All the arms in all the world might be at your disposal, but if you’re not going to pick one up to defend yourself, what incentive is there for a potential attacker to not do so? Coupled with existing policies that constrain state behavior – and the longstanding norm, for practical and moral reasons, that the United States is not inclined to conduct nuclear strikes – it’s hard to see how a slightly more useful weapon wouldn’t bolster national deterrence efforts (which again, is one of the main reasons to have these weapons in the first place).

One might even shock some of the cruise missile opponents by theorizing what the weapons effects might actually be in a conflict. If the United States were to find itself in some sort of situation where nuclear usage seemed imminent, wouldn’t a discriminate weapon – designed to minimize collateral damage and ensure accurate, precision targeting – be the preferred choice? There are few instances with conventional munitions where an older, less precise model has been maintained despite the availability of newer technology. Nuclear weapons should hardly be an exception to this. Instead of the “city-buster” of old, moving towards “block-buster” and even smaller areas of effect should be the goal. Utility is of far more than marginal consequence when it comes to a national deterrent.

The NNSA/DoD 3+2 Strategy, designed to consolidate the total number of warhead designs in the stockpile.

The NNSA/DoD 3+2 Strategy, designed to consolidate the total number of warhead designs in the stockpile.

Even more paramount, in the history of the US nuclear weapons program, is safety. The United States and its atomic establishment pioneered technologies and concepts like Permissive Action Links and “one-point safe.” Given the age of the nuclear arsenal – and again, abolitionists’ refusal to develop much in the way of new warhead designs – the safest option for the aging B61 is to consolidate all the various “mods” into the B61-12, and likewise most of the W78 and W87 mods current used to arm ballistic missiles (this project is known as the “3+2 Strategy.” This also allows the arsenal size to be reduced, along with the total megatonnage. Indeed, as the National Nuclear Security Administration puts it in the FY16 Stockpile Stewardship and Management Plan:

While the 3+2 Strategy will take 30 or more years to implement fully, implementation has begun with the B61- 12 LEP. The B61-12, now nearing the end of the second year of full-scale engineering development, will enable the consolidation of four families of the B-61 bomb (the -3, -4, -7, and -10 variants) and will improve both the safety and security of the oldest weapon system in the U.S. arsenal. The B61-12 is currently scheduled for a first production unit in FY 2020 . Once the B61-12 LEP is completed, following roughly a four-year build and once confidence is gained with B61-12 weapons in service, the B83 — the last megaton- class weapon in America’s arsenal— will be retired. The combination of these events will result in (1) a reduction in the number of bombs by a full factor of two, (2) the removal of a megaton-class weapon, (3) a reduction in special nuclear material of more than 80 percent in the bomb portion of the air leg, and (4) a reduction in the overall destructive power by a commensurate factor.

Unless the credibility of US deterrence is based on unusable, large-yield weapons, this would seem to be a net win both for arms controls and disarmament as well as strategic competition and credibility at a time when adversaries are modernizing and upgrading. But sadly, this debate always seems boils down to an attempt to insist on unilateral disarmament by default, as the existing arsenal rusts its way into oblivion without a replacement on the horizon. The Department of Defense is not considering growth in the nuclear force – the country will continue to adhere to New START limits and restrictions – but rather, replacement of aging and worn systems that the nation already has. Sadly, even replacement on a one-to-one basis is often characterized as “expansion” when in reality it is a sorely overdue modernization effort that preserves, if not lowers, total numbers, and drastically reduces the total yield of the stockpile.

A low-yield, high-precision nuclear weapon isn’t a specter of imminent nuclear conflict. It’s a reasonable replacement for a weapon past its prime. It’s a capability we already have, which is need of a material upgrade and which has served as a critical part of the US arsenal for decades. Inventing new dangers is an egregious means of arguing against maintaining even current levels of technology.


3 thoughts on “The “Utility” of Low-Yield Nuclear Weapons

  1. “Given the age of the nuclear arsenal – and again, abolitionists’ refusal to develop much in the way of new warhead designs – the safest option for the aging B61 is to consolidate all the various “mods” into the B61-12.”

    Reflecting on the merits of the B61-12 as I saw them presented by the NNSA, STRATCOM and Senator Kyl to Congress in late 2009, I don’t recall abolitionists cited as influential in the design selection. From the outset of the Obama presidency, the mission of the NNSA was to reduce the footprint of the nuclear weapons complex through stockpile modernization. The B61-12 was a natural extension of that initiative, some would say it wasn’t the best, but I don’t think the NNSA acquiesced any noble dream for a new warhead design for the sake of this LEP.

    It’s critical not to exaggerate the influence of abolitionists in electing a warhead design, otherwise you confound the appropriation of power in American nuclear policy. Despite their tyranny, America’s obligations under current arms control treaties are flexible enough for the requirements of the NNSA, and funding for the complex has been resilient across administrations.

  2. That’s certainly fair – what I was trying to get at is that with the Obama Administration adopting an abolitionist (or maybe “abolitionist-inspired” would be more accurate) policy as of Prague, meaning no new warhead designs, the next safest thing to do is consolidate mods.

    I mean, if the national labs had their druthers, we’d be looking at all sorts of interesting next-generation warhead designs, I’m sure. But given existing policy constraints, the mod 12 would probably be necessary even solely from a safety perspective, much less a flexibility one.

  3. Pingback: Obama at Hiroshima: A Fitting Capstone on Nuclear Weapons American Security Project

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