War clouds on the Korean peninsula: What would we do if…?

Anyone who has been following the news lately knows that both Kim Jung Un and Donald Trump have escalated their war rhetoric and that one US intelligence agency (DIA) has concluded that North Korea has successfully produced a miniaturized nuclear warhead that can fit inside its missiles. Yesterday, the President said that his earlier “fire and fury” comments were perhaps not tough enough towards North Korea, and today he said that “military solutions are now fully in place, locked and loaded” should North Korea act unwisely.

So it’s worth considering what the United States and/or South Korea might do under a variety of scenarios. It’s pretty clear that if North Korea actually launches a nuclear-tipped missile that explodes and causes large-scale casualties in Japan, South Korea, the United States, or anywhere else, nuclear retaliation against North Korea is likely. And it is inconceivable that plans for nuclear strikes against North Korean targets have not already been developed.

More difficult to predict are the outcomes in a number of scenarios that are still provocative and escalatory but less serious than those resulting in large-scale casualties. Consider the following:

1. Carrying out the threat recently issued by North Korea to launch several (presumably unarmed) missiles into waters near Guam, but in international waters. (Assume that after launch, radar tracks of these missiles indicate that they will miss Guam by dozens of miles.)
2. A demonstration use of nuclear weapons by North Korea, in which a nuclear-tipped missile is launched into the Pacific Ocean and detonates near sea level far from any land mass, causing no casualties.
3. The same scenario as above, except that in this variant, a small civilian ship is by chance close enough to the detonation to be seriously damaged, with a few deaths resulting.
4. The use of a few shorter-range missiles carrying conventional warheads against the territory of South Korea or Japan, coupled with an explicit threat to launch nuclear weapons if the United States responds militarily.

In Scenario 1, no casualties occur and no property is destroyed. Is an action that results in no casualties and no property damage worth a military response that will lead to a North Korean counter-response that will with 100 percent certainty cause large-scale death and destruction? During the missiles’ flight, should the United States try to intercept them, knowing they will not come anywhere near Guam? (The interceptors might miss—with all of the political consequences of missing—and in any event, an attempt to intercept on harmless missiles would needlessly use up interceptors that might be needed later.)

Scenario 2 involves the open-air detonation of a nuclear weapon. Such a detonation outside North Korea is obviously provocative, but North Korea is not a signatory to the Limited Test Ban Treaty forbidding open-air testing of nuclear weapons. And again, no one dies. What then?

Scenario 3 causes death but unintentionally and “only” on a very small scale. It’s difficult to imagine North Korea apologizing or paying reparations for such an outcome; much more likely is unrepentant defiance. North Korea has previously taken military actions that resulted in death on a small scale, but used ordinary conventional weapons. Deaths resulting from the use of nuclear weapons are unlikely to be regarded in the same way.

Scenario 4 is definitely a military attack against a US ally, and by treaty would warrant US military intervention. But if the damage caused is small, and no other North Korean military actions are forthcoming, what is the nature of the appropriate US military intervention? A nuclear response seems inappropriate—and in that case the possibility of a nuclear counter-response from North Korea may well deter the United States from any kind of intervention. So what would the United States do?

I don’t have any good responses to these scenarios. I pose them because the predominant focus of policy-maker attention seems to be on extreme scenarios that involve serious death and destruction. That’s perhaps understandable under the circumstances, but North Korean actions today need not involve large departures from past practice. Any of these “smaller” steps could still have major escalatory consequences—and policy makers would be well-advised to think about what to do should these eventualities occur.