The U.S., South Korea, and Japan are afraid that North Korea will hit them with a nuclear missile.  So, the U.S. is going to nuke North Korea first??  Does that seem logical?

If anything, the U.S. might launch non-nuclear cruise missiles at some North Korean military base like they did in Syria.  That would be a mistake also since North Korea might read that as an invasion and retaliate with all their forces, meaning devastation of South Korea and some parts of Japan.

Any preemptive strike by the U.S. will be a huge mistake.