A war with North Korea is coming either way.
And so the U.S. has two broad policy options to deal with this reality: It can respond after a North Korean nuclear strike triggered by a false alarm, or it can launch a pre-emptive strike that eradicates the Kim regime and degrades North Korea’s ability to inflict harm upon the U.S. and its allies to the greatest extent possible.
Given North Korean defensive measures, this effort will almost certainly require the use of tactical nuclear weapons. As horrible as a war with North Korea will be, the war will undoubtedly be far less horrible if it begins with a U.S. pre-emptive strike rather than with a North Korean first strike. It is as simple as that.