Slipping Towards North Korea
This week American media are finally recognizing the most likely path to armed escalation of the North Korean nuclear standoff, which I have blogged about since last winter. But commentators are only waking up to the possibility because the Donald Trump administration has started to suggest it. In scenario being discussed, the U.S. (and perhaps also Japan) could begin to intercept North Korean ballistic missiles with either of the two kinds of anti-missile system now deployed in the region. Routinely shooting down North Korean missiles would prevent successful tests and would also signal to the Kim Jong Un regime that its missile attack capability could be neutralized. If this level of violence were initiated, the question is whether North Korean retaliation would lead down the slippery slope to a wider war.
Until now, the media have not grasped this scenario. To the extent that there was any public consideration of intercepting North Korean ballistic missiles, the focus had been on terminal interception, either over South Korea using the newly deployed THAAD missiles there or, if a North Korean ICBM targets the U.S. itself, over North America using the ABM interceptor missiles operational in Alaska. This focus on terminal interception as the missile’s warhead is re-entering earth’s atmosphere is a legacy of the Cold War, when the principal threat to North America was thousands of Soviet ICBMs and SLBMs each deploying multiple warheads. In that context of potentially tens of thousands of simultaneous warhead targets speeding to earth, ABM defenses were correctly discerned to have a near-impossible and certainly uneconomic task. Buying more ABM defenses would just lead to the adversary overmatching them with even more incoming missiles. Furthermore, detecting and reliably intercepting a small ballistic warhead plummeting earthward at hypersonic velocity remains a serious technical challenge. The relatively low success rate of test interceptions attests to this.
However, North Korea is not the Soviet Union. It is a much smaller and poorer country than were the Cold War superpowers. Size matters because Soviet missiles would have been launched either from scores of submarines at sea or the interior of the world’s largest nation. The launch of missiles can be detected from spy satellites in space, but there is no means to attack them while they accelerate through the atmosphere from the middle of a vast country. North Korea lies on a narrow peninsula, allowing U.S. warships proximate access off its coasts to cover the country’s entire airspace with interceptor missiles, specifically the U.S. Navy’s SM-3, guided by the shipboard AEGIS radar system. All 84 U.S. cruisers and destroyers are equipped with these, as are some Japanese warships. The range and high speed of the SM-3 gives it a reasonable chance to shoot down North Korea missiles during their boost phase, as they accelerate into space. This is a much easier feat than terminal interception because the target is larger and more vulnerable (a missile full of explosive fuel), and is moving at a much slower relative velocity. North Korean ballistic missiles are not only vastly fewer than those the U.S. faced during the Cold War, but also much more vulnerable to interception.
This is why, as I suggested last week, the world could live with North Korea having ballistic missiles and nuclear weapons. North Korea still cannot be a secure nuclear power, as the Cold War superpowers were in the 20th century or the U.S. and Russia are today. Nuclear weapons do not actually reduce North Korea’s vulnerability. Instead they increase it: In a crisis, they may heighten the urgency to pre-emptively strike to destroy North Korean missiles before they can be launched.
It helps to remember why the Cold War “balance of terror,” or “mutual assured destruction” (MAD), deterred war between the U.S. and the Soviet Union. What MAD means is that neither side has an incentive to start a war because even with the advantage of a surprise first strike, so much of the adversary’s nuclear force would survive that its counterattack, or second-strike capability, could still devastate the attacker. Thus in a crisis the rational choice is to back down and avoid escalation rather than risk mutual annihilation.
However, this deterrence logic only works if there is no decisive advantage to striking first. It has always been easier to destroy nuclear missiles on the ground before they are launched than it is to intercept them in the air with ABM defenses. Even though both the U.S. and the Soviet Union placed their ICBMs in underground silos, such was the power and accuracy of nuclear missiles that each side could expect to knock out many, if not most, of their enemy’s ICBMs in a first strike. However, since each side had more than a thousand silos, even eliminating most of them would leave enough survivors for a devastating second strike. Furthermore, SLBMs based on submarines at sea, always moving, cannot be detected and targeted the way fixed silos can. Today, several countries have ICBMs that are mobile on large trucks, which is another way to escape destruction in a first strike. This keeps nuclear deterrence stable—it is unlikely a potential attacker can expect a first strike could knock out all or nearly all of an enemy’s forces.
North Korean nuclear forces can never be so secure. First, they are few, so most if not all could be destroyed in a first strike. Second, those that might survive a first strike would likely be few enough that ABM systems near Korea could destroy any that are launched during the boost phase. If a handful survived that, they might still be intercepted during terminal re-entry. In fact, even without a first strike, if the number of missiles is dozens rather than thousands (which is likely given North Korea’s limited resources) then a first strike is not even necessary. Even if North Korea struck first, it is likely that most if not all of its missiles could be intercepted. Numbers do matter, up to a point.
Politically it is a double-edged sword for the Trump administration to admit that it has sufficient capabilities to intercept North Korean ballistic missiles. On the one hand, this seems like a potent way to neutralize the North Korean threat short of all-out war. On the other hand, if it appears easy to counter the North Korean ballistic missile threat, that also tends to contradict the fear-mongering and hype surrounding the existential threat North Korea supposedly poses to the world. The administration can’t have it both ways. Either North Korea is a dire threat or it is not. I contend that existing U.S. capabilities, if alert and deployed, are adequate to deter North Korean aggression. Kim Jong Un is still free to exploit the same bombastic and threatening rhetoric he has employed for years, but an educated public is free to ignore him, confident in the ability of vastly greater powers that isolate, deter, and constrain North Korea.
Yet Trump, having criticized previous administrations for being “soft” on North Korea and amplifying the threat, cannot easily make it go away. As I argued last week, economic sanctions are not likely to work. North Korea’s isolation and its consequent obsession with national defense make nuclear weapons too attractive to a regime that feels under chronic threat. Trump may be forced by the logic of his own rhetorical devices to actually begin intercepting North Korean missiles rather than just talking about it. Otherwise he looks weak, drawing “red lines” that Kim Jong Un violates with impunity. But if he does shoot down missiles and North Korea responds provocatively—for example, by sending submarines to shadow the U.S. ships that conduct the intercepts—then war may erupt from a process of tit-for-tat escalation. As I argued from the start, this may not be unintentional, even if Trump wants his action to be seen as purely defensive. Ultimately the unstated goal may be defeat of the North Korean regime.