Former U.N. ambassador John Bolton is calling for a pre-emptive strike on North Korea to destroy its nuclear and missile programs, which already may be capable of striking the U.S. mainland.

Bolton makes a convincing case in the Wall Street Journal.

Pre-emption opponents argue that action is not justified because Pyongyang does not constitute an "imminent threat."  They are wrong.  The threat is imminent, and the case against pre-emption rests on the misinterpretation of a standard that derives from prenuclear, pre-ballistic-missile times.  Given the gaps in U.S. intelligence about North Korea, we should not wait until the very last minute.  That would risk striking after the North has deliverable nuclear weapons, a much more dangerous situation.

In assessing the timing of pre-emptive attacks, the classic formulation is Daniel Webster's test of "necessity."  British forces in 1837 invaded U.S. territory to destroy the steamboat Caroline, which Canadian rebels had used to transport weapons into Ontario.

Webster asserted that Britain failed to show that "the necessity of self-defense was instant, overwhelming, leaving no choice of means, and no moment of deliberation."  Pre-emption opponents would argue that Britain should have waited until the Caroline reached Canada before attacking.

Would an American strike today against North Korea's nuclear-weapons program violate Webster's necessity test?  Clearly not.  Necessity in the nuclear and ballistic-missile age is simply different [from] in the age of steam.  What was once remote is now, as a practical matter, near; what was previously time-consuming to deliver can now arrive in minutes; and the level of destructiveness of nuclear, chemical and biological weapons is infinitely greater than that of the steamship Caroline's weapons cargo.

Daniel Larison, writing in the American Conservative, disagrees:

The concepts of preemption and imminent threat have been so thoroughly warped by the Iraq war debate that their proper meanings have been all but lost.  Preemption means striking before an impending attack occurs, but there is no such attack being prepared by North Korea.  If the U.S. strikes North Korea first under these circumstances, our government would be committing an act of aggression pure and simple.  There would be no preemption, because there would be no attack to preempt.

Bolton declares that the threat from North Korea is imminent, but this requires us to redefine imminent to mean something entirely different from what it has always meant.  Imminent means something that is about to happen, and that does not describe the threat from North Korea.  North Korea is not about to attack the U.S. or its allies.  It is not about to do it next month or next year.  It is not about to do it at all.  It has been deterred from doing so for decades, and continues to be deterred.  In order to believe that there is an imminent threat from North Korea, namely one that is going to happen in the very near future, one also has to believe that its government is bent on self-destruction.  Bolton writes about North Korean nuclear weapons and missiles as if their mere existence justifies a U.S. attack, but that is simply nonsense.

Larison totally ignores the points about "imminent threat" that Bolton makes.  As Bolton writes, the legal definition of "imminent threat" that underpins international law was written in the age of steam.  Common sense and prudence makes that definition – Webster's "necessity" test – not applicable to present circumstances.  I don't recall whether Larison criticized President Obama's decision to bomb ISIS, which did not represent an "imminent" or "existential" threat to the U.S.  But it was the right call, albeit weakly carried out.  Should we have waited to strike until ISIS grew larger and more powerful?  That's an absurd notion.

Larison believes that North Korea is "deterred" from attacking because its government is not "bent on self-destruction."  In fact, there is a huge element of uncertainty about that.  We simply don't know what's in the mind of Kim Jong-un or the top leadership of North Korea, because they are one of the most closed and paranoid societies in human history.  It is that level of uncertainty that justifies a strike.

I understand where Larison is coming from.  How can any rational leader deliberately carry out an act that is guaranteed to bring about his destruction?  Kim may be rational, but not as you or I – or Larison – understand the concept. 

There are still the enormous costs and risks to weigh before Trump might pull the trigger.  North Korea will not go quietly, and the almost certain retaliation against South Korea with the North's 50,000 artillery pieces putting Seoul in range of merciless destruction must be considered soberly.  And who knows whether we would be able to stop the North from launching a missile or missiles toward the U.S.?  As with the Cuban crisis in 1962, any strike would not guarantee that we'd get all the missiles.  Some may be fired.  And it takes only one hit to cause unbelievable chaos and destruction.

I agree with Bolton's assessment of the legal case for war.  But on a practical level, it may be impossible to avoid widespread destruction both in the U.S. and the region.  It's a tough call and one that Donald Trump will almost certainly have to make in the near future.