The Times report on preventive war thinking in the White House starts off on the wrong foot:

Not since 2002, as the United States built a case for war in Iraq, has there been so much debate inside the White House about the merits — and the enormous risks — of pre-emptive military action against an adversary nation.

It is worrisome that administration officials are debating an attack on North Korea in any case, since the likely consequences would be disastrous for U.S. allies and for Americans in South Korea. Because the National Security Advisor has publicly (and, in my view, dishonestly) rejected the idea that North Korea can be deterred, this debate inside the White House is even more alarming. The problem with the article’s framing is that the attack being considered has nothing to do with pre-emption as it is properly understood. Pre-emption is an extreme but nonetheless potentially valid form of self-defense. An attack on North Korea would be preventive war of the most stupid and dangerous kind, and the public needs to understand that it has nothing to do with self-defense.

If the U.S. attacked North Korea, it would be doing so illegally and without justification. Preventive war cannot be defensive by definition, and so there is no sense in which it can be waged as a last resort. Preventive war is inherently unjust, and the U.S. should never wage such a war. If Trump ordered a preventive war against North Korea, he would have no authority to do so. He would be acting in violation of U.S. and international law, and he would be launching nothing less than a war of aggression. Regardless of what one thinks U.S. policy should be, it should be easy to agree that illegal, aggressive warfare is unacceptable.