Michael KreponStale Thinking on Tac Nukes Reheated

Quote of the week:

“Neither a viable posture nor a viable doctrine exist … for the employment of tactical nuclear weapons.”
—William R. Van Cleave and S.T. Cohen, Tactical Nuclear Weapons (1978)

As the confrontation with North Korea builds, there is growing sentiment within South Korea to reintroduce U.S. tactical nuclear weapons withdrawn when the Cold War ended. Concurrently, there is another boomlet in Washington for new tactical nuclear weapons in the run up to the Trump Administration’s nuclear posture review. Both ideas are unwise and deserve once again to be rejected.

The quote from Van Cleave’s and Cohen’s book was a lament as well as an acknowledgement of reality. They wanted the U.S. Army to take tactical nuclear weapons more seriously, but after going overboard in the 1950s and 1960s, the Army leadership increasingly held the view that they were more of a hindrance than a help in fighting ground campaigns. After the Cold War ended, the Army rid itself of the nuclear mission and hasn’t looked back. If tac nukes are to be used in a war on the Korean Peninsula, the Air Force will do the deed.

Van Cleave’s influence was never greater than during the first Reagan Administration, where he served as an advisor. For the most part, however, he defended nuclear orthodoxy and mentored from university perches. Cohen is perhaps best known as the “father” of the “neutron bomb” (or “enhanced radiation weapon”), designed to maximize radiation while limiting blast effects when used on battlefields or urban areas.

The neutron bomb made good sense to Secretary of Defense James Schlesinger and other nuclear strategists as a way to counter Soviet tank armies advancing across Europe. But it didn’t make sense to many in Europe who declined to be defended by enhanced radiation weapons. The neutron bomb was easily caricatured by the anti-capitalist Left as a weapon to kill people rather than damage property. President Jimmy Carter didn’t need much convincing to walk away from the neutron bomb, which he viewed as an unwanted inheritance from the Ford Administration.

Both Van Cleave and Cohen are no longer with us, but their views haven’t died. Supporters of a new tactical nuclear warhead design advance two arguments: First, there is a tactical nuclear weapons “gap” with Russia and, second, the Pentagon needs to modernize a Cold War-oriented stockpile to meet post-Cold War threats like that from North Korea. There is a sotto voce argument, as well: the designers of the Cold War stockpile are retiring or retired, and their younger replacements need to cut their teeth on a new design.

The arguments for adding another low-yield warhead design to the current U.S. stockpile don’t add up. The stockpile already includes three warhead types whose yields can be dialed way down or up. To deal with post-Cold War threats, advocates argue that small mushroom clouds are better than big mushroom clouds. They also believe it is important to have rungs for escalation and escalation control in nuclear exchanges. But if large mushroom clouds are insufficient as a deterrent, small mushroom clouds are unlikely to be more persuasive.

The fixation with tactical nuclear weapons reached its apogee in the 1950s and 1960s, epitomized by Herman Kahn’s tome, On Escalation: Metaphors and Scenarios. Published in 1965, Kahn suggested a notional escalation ladder of no fewer than forty-four rungs. In Kahn’s fertile mind, signaling escalation and escalation control was akin to buying a new Studebaker from the dealer and haggling over the price. I’ll see your five kilotons and raise you ten. Your move.

To give Kahn his due, he recognized that

“All bargaining, at the upper as well as lower rungs of the escalation ladder, is bound to be complicated by the fact that each side’s information would be different; each side might be attempting to bluff the other side, to give misleading information; there would be communication difficulties; there would be the pressure of time; there would be a play to emotions, irrationality, anger, miscalculation, bad doctrine, misapprehension, mistake, and shock.”

Even so, these complications could be tamed, in Kahn’s view, by analytical rigor, just like like his rungs up the escalation ladder. Kahn’s confidence never wavered. For him, the problem of the “fog of war” was subject to “systematic overestimation.” Here, he employed the analogy of a ship’s captain who could chart a course through a blinding fog:

“One of the greatest misconceptions current in discussions of command and control is a failure to understand how well a central war might be run, at least initially, by ‘dead reckoning.’

“The commander or decision-maker may know a good deal about how the war started and the basic conditions existing at the outbreak … From this point forward, even though he is completely cut off from all information external to his own organization and forces, and perhaps even from much of that, he may still have enough of an idea of events and their timetable, at least in outline, and a sufficient judgment of what the other side is trying to accomplish (through knowledge of its logistics, forces, doctrine, and other constraints) to ‘play’ both sides hypothetically by dead reckoning – adding and correcting with whatever information comes in.”

Kahn clearly went overboard here and elsewhere. The more detailed speculation he provided, the more obvious it became that, despite his brilliance, he lacked basic common sense. Deterrence strategists who avoided detail were on firmer ground, but they, too, avoided the central question of how a nuclear war ends. If two states have screwed up so badly that they have used nuclear weapons on a battlefield, how are they supposed to agree on numbers and yields?

Today’s situational awareness may be well beyond even Kahn’s imagining. But the sensors that provide situational awareness could also be messed up once the nuclear threshold is crossed. The basic assumptions behind the use of limited nuclear options remain breathtakingly facile. It’s folly to assume that nuclear exchanges can be tidy and that nuclear weapons can be domesticated by downsizing yields. Or that command and control can be maintained on a nuclear battlefield. The dominant impulse once the balloon goes up will most likely be to speed up, rather than slow down decision making. Until advocates of limited options for the battlefield use of tactical nuclear weapons and new warhead designs can explain to us how this war ends, they cannot make a sound case.

Still, tactical nuclear weapons haven’t gone away. They have become crutches for weak states to deter stronger ones. If the weaker state crosses the nuclear threshold first to make it harder for the stronger state to advance, does it make sense for the stronger state to compound difficulties for its ground operations by retaliating in kind?

The United States, which enjoys conventional military superiority, powerful allies, and possesses a few thousand operational nuclear weapons with widely varying yields, doesn’t need to match up against an adversary’s tac nukes. Instead of fighting fire with fire, the Pentagon can fight fire with very high-pressure water hoses. Put differently, the way to beat tactical nuclear weapons is with overwhelming conventional and air power. There are no targets for small mushroom clouds that conventional capabilities can’t handle. And if conventional firepower isn’t effective enough, then small mushroom clouds won’t help, either.

Nuclear soothsayers tell us that it’s not about battlefield use; it’s all about deterrence. But the point of deterrence is no mushroom clouds, not tailor-made, low-yield mushroom clouds for escalation control and battle management. Protecting allies with the neutron bomb was a bad idea in the 1970s; protecting them in the 2020s with a new tactical warhead design is also a bad idea.

Even with expensive bells and whistles, deterrence has already failed twice between nuclear-armed states that fought limited wars over contested borders — China and the Soviet Union in 1969 and India and Pakistan in 1999. These wars ended in draws, as did the Korean War. A second war on the Korean Peninsula would result in U.S. victory, but if North Korea isn’t asleep at the switch, victory will almost certainly come at high cost. The re-introduction of tactical nuclear weapons that George H.W. Bush removed from South Korea won’t change this bottom line.

When it comes to capabilities for nuclear warfare, better is the enemy of good enough. Bells and whistles are not just expensive, they might also require the resumption of nuclear testing by the United States — and by Russia, China, India and Pakistan. Depending on who goes first, the progression of resumed testing might vary, but the results would be equally catastrophic to the nuclear safety net woven patiently by earlier generations. Giving a rising generation of laboratory scientists practice in designing a new warhead isn’t worth these costs.

As for the redeployment of tactical nuclear weapons back to South Korea, we are told that this is needed to reassure a jittery ally or to help prevent Seoul from seeking its own nuclear deterrent. Neither argument can withstand serious scrutiny. Land-based nuclear weapons in South Korea are not reassuring, nor are they needed. The United States is already signaling readiness to come to South Korea’s defense, including by nuclear weapons’ use, by many other means, including bomber over-flights. These signals have not altered Kim Jong Un’s behavior. Repositioning tactical nuclear weapons won’t, either.

As for the nonproliferation argument, as long as Washington and Seoul remain strong allies, South Korea will not build nuclear weapons. All bets are off, however, if the Trump Administration initiates a war on the Korean Peninsula featuring heavy casualties and mushroom clouds, whether small or large. The surest path to nuclear proliferation in South Korea and elsewhere is for Trump to ruin alliance ties.

Note to readers: A shorter version of this essay was published in DefenseOne on October 2nd. 


  1. AEL (History)

    Why do you think that a second Korean war would end in a US victory? Don’t forget that China has a friendship treaty with North Korea and is bound to its defense.

    • Simon Gunson (History)

      I totally agree with AEL. My understanding is on August 11th China indicated if North Korea is attacked it will intervene, however nowhere has China suggested it will back or support a US invasion. An attack on North Korea could quite likely result in a full nuclear exchange between China and USA.

      There seems to be a gross underestimation too by Hawks in the US of North Korea’s capabilities. Almost a sneering contempt.

      I am reminded of the naval blockade against Japan by the ABDA naval flotilla to enforce Franklin Delanor Roosevelt’s Executive Order 8832 Just as North Korea is today subject of a total economic blockade, so too was Japan. In July 1941 Americans also scoffed that Japan was a puny military power unable to threaten the US. What came next was a devastating and unexpected attack on Pearl Harbour

    • Andrew Locke (History)

      The Chinese government publicly stated through a recognized national news outlet that it will not aid North Korea if it attacks US soil first (https://www.washingtonpost.com/world/china-warns-north-korea-youre-on-your-own-if-you-go-after-the-us/2017/08/11/a01a4396-7e68-11e7-9026-4a0a64977c92_story.html?utm_term=.f443a7db25d3). Now, what exactly would constitute “US soil” is the really important question. Would it include an ally that the US is bound by a similar agreement to protect, like Japan? Would it include a territory like Guam? Would it even include a malfunctioning test of a missile with a live nuclear payload, like North Korea’s Foreign Minister said may be attempted, that results in disastrous consequences for the nation that it lands upon, like Japan? What if a North Korean “Juche Bird” detonates at such a high altitude over the North Pacific that it results in an EMP over a relatively wide area, bringing down dozens of commercial airliners as a result, killing thousands from a whole variety of nations? I think it’s fairly safe to say the US would prevail militarily in a resumption of hostilities with North Korea (the war technically never ended) if the fighting takes place strictly between the two countries, without outside intervention, but at what cost, and to whom? A devastated, possibly radioactive North Korea where millions of men, women and children have died? A devastated North America, reeling from an EMP attack that got through the GMD system, that condemns tens or even hundreds of millions of people to die over months and years from exposure, disease, dehydration, malnutrition, and civil strife? This is what is at stake here, not just a US city or two, or Pyongyang. This is the reality of the horrific power of nuclear weapons, which the US and North Korea are both equipped with, and the knowledge of how to employ them in 2017. If these dogs of war are “let slip”, the bets are off, the consequences uncertain, and the Reaper very busy.

    • Jonah Speaks (History)

      I think the Chinese are likely to employ some common sense when deciding whether and how to assist North Korea, in the event of a U.S. attack on North Korea. Did North Korea start the war, or did the U.S.? Is the U.S. attempting a conventional attack on North Korea’s nuclear weapons, or trying to overthrow the Kim regime? It seems unlikely that China and U.S. would enter into a nuclear war with each other over North Korea. More likely is a war contained within the Korean peninsula, unless North Korea decides to use its nukes outside Korea.

      I don’t see how the U.S. military can easily disarm DPRK’s nuclear arms, and the downside of trying ranges from dismal to catastrophic.

    • Andrew Locke (History)

      There are things we are not really privy to in terms of just what the US can do to disarm North Korea, things that are classified and for good reason. I am not suggesting it would be risk-free. Per some of my other posts, my greatest fear is NK getting off an ICBM shot that the US is unable to intercept, which results in a nuclear high-altitude EMP that craters the electrical grid and most electronic devices in North America, resulting in the eventual destruction of civilization in the US, Canada, and probably Mexico. North Korea is a country in the relative infancy of being able to reliably threaten us like that. Do we want to wait until the literal Sword of Damocles in hanging over us 24/7, or do we want to act now while the sword is being slowly but inexorably grasped and hoisted? Diplomacy is great when it works, but when it fails, you do have to be ready to use the stick, or it will be used upon you. Simon Gunson brings up the example of US actions towards Japan apparently leading to Pearl Harbor. I find myself thinking of Germany in the 1930’s, of the growing Nazi threat and what ignoring it, accommodating it, and denying it eventually resulted in. Europe and Asia, just like South Korea of today, was right next door to the developing nightmare. Europe and Asia too had no luxury of distance, no convenience of geography to enable the threat to be dealt with in a more convenient and less expensive way, and so they dallied and dithered too, trying to postpone the inevitable. Eventually Europe, the Soviet Union, the US, and the Commonwealth paid a terrible price for this, when Germany unleashed it’s military. North Korea’s leadership believes in an inevitable reunification with South Korea, on their terms, not South Korea’s, and they see nuclear weapons as the means of ensuring not only a “Juche”-type self-reliance for their self-defense, but also freedom from interference in assimilating a US ally and democratic country that happens to be the World’s 11th-largest economy. This cannot be allowed to happen, and I am pretty sure won’t be. I don’t see North Korea “pulling over”. I don’t see the US denying the use of military force as an option. The way things are evolving, it is just a matter of when, not if.

    • Jonah Speaks (History)

      To assess the long-term consequences of allowing Kim to proceed with his nuclear and missile development, we need to know Kim’s intentions. I see three possible reasons for Kim’s nuclear development: 1) Kim is primarily interested in raising his prestige to strengthen his grip on power. 2) Kim is primarily trying to deter U.S. invasion or attack. 3) Kim is primarily seeking to invade or coerce South Korea without U.S. interference. I see (1) as most likely and (2) as least likely, leaving perhaps a 1/3 chance that (3) is true.

      Suppose (3) is true, in order to have an effective plan to coerce South Korea, Kim must be able to invade and conquer with conventional forces alone. If he cannot, nuclear threats alone won’t coerce South Korea. It’s also unlikely that Kim’s nuclear threats can drive a serious wedge in the alliance. The reason is quite basic: If Kim ever acts on his nuclear threat, he dies.

    • Andrew Locke (History)

      I think that the purpose of North Korea’s current nuclear weapons and missile development program is really a combination of your second and third choices; Kim Jong Un is seeking to deter the US from attacking North Korea via the development of a nuclear arsenal capable of holding the mainland US at risk. He has also been consistently outspoken in his stated desire to re-unite North and South Korea, by force if necessary, and wants to be able to do so without US interference. I think that North Korea originally started developing nuclear weapons as a means of securing some sort of national prestige, slowly proceeding along those lines, but under the current regime, an intent to deter the US has been the primary focus. This is evidenced by Kim Jong Un’s fast-paced nuclear device and missile testing program, including ones with truly intercontinental range, and his repeated threats to use them against the US in language that is pretty unambiguous. If North Korea wanted only to threaten and coerce South Korea, they wouldn’t bother developing ICBMs, as they have plenty of conventional forces to accomplish that task. Let’s not forget that North Korea also possesses chemical and possibly biological weapons as well, providing additional means of threatening South Korea. I am sure that Kim Jong Un understands that if he uses nuclear weapons, he is inviting his own destruction; he wants not to use them, but to create a mutual deterrence relationship between his country and the US, one where the US feels that the possible costs of undertaking conventional military action against his country are not worth the possible risks of escalation. I think that Trump wants to prevent them from achieving that level of nuclear capability, feeling that it is better to strike now when North Korea has just a few missiles capable of reaching the US, versus waiting until they have sufficient numbers to effectively deter the US from acting to protect South Korea. North Korea’s fear of being pre-emptively attacked is likely why they decided to specifically describe their new thermonuclear device, when it was unveiled hours before the September 3 2017 test, as designed for an EMP attack against the US. Since an effective EMP attack would only require several such devices and would inflict an unacceptable level of destruction on the US, it is undoubtedly seen by them as a means of utilizing the smaller number of missiles and warheads they possess to counter and deter the much larger and more powerful nuclear forces of the US.

    • Jonah Speaks (History)

      Re Trump’s hypothetical “feeling that it is better to strike now when North Korea has just a few missiles capable of reaching the US, versus waiting until they have sufficient numbers to effectively deter the US from acting to protect South Korea.” Suppose we know for a fact that North Korea intends to invade or coerce South Korea, and that North Korea’s nuclear weapons would successfully deter the U.S. from intervening. What then?

      Trump has already suggested an answer: South Korea should get its own nuclear weapons. Perhaps South Korea should be granted a temporary reprieve from the NPT, pending denuclearization of the Korean peninsula. This would balance out the illegal advantage North Korea has obtained by harboring chemical, biological, and nuclear weapons. Hence, Trump would need to explain why war now is better than a nuclear South Korea.

  2. Bradley Laing (History)

    The US Will Be Dropping A Lot More Bombs on Afghanistan

    More air support for Afghan forces will help drive the Taliban to the negotiating table, Mattis and Dunford tell Congress


    —If this works, when do we know it works. If it does not work, when will we know it will not work.

  3. Jonah Speaks (History)

    The main issue for tactical nukes is not the type of weapon, but its proposed manner of use. In particular, does the nuclear policy or strategy permit first use of nuclear weapons, or does it only permit second use? During the Cold War, NATO starting a strategic nuclear exchange in response to an invasion of Europe would have been suicidal folly. Hence, NATO wanted limited nuclear war options that might deter such an invasion, while limiting the risk of setting off a strategic exchange.

    Avoiding a full-scale nuclear exchange requires that both sides follow a set of rules for nuclear war. One possible rule is that each side only uses tactical nuclear weapons aimed at military targets. Another possible rule is that each side bombs only one city at a time. Since it is unlikely that both sides will follow the same set of rules, any nuclear use is likely to escalate into mutual nuclear destruction. This means any nuclear first use is highly inadvisable.

  4. Bradley Laing (History)

    Please use the sharing tools found via the email icon at the top of articles. Copying articles to share with others is a breach of FT.com T&Cs and Copyright Policy. Email licensing@ft.com to buy additional rights.

    A trove of classified military documents, including the joint South Korea-US wartime operational plans for a conflict with Pyongyang, are believed to have been hacked by North Korea, a lawmaker in Seoul said on Tuesday.

    Lee Cheol-hee, a lawmaker with the ruling Democratic party, said hackers broke into a defence data centre in September last year to steal sensitive documents, including Operational Plans 5015 – the most recent allied plans to fight North Korea in all out war.