He might actually have the ability to do it. He certainly doesn't have any moral qualms. Oh sure, it would invite retaliation so massive, he would surely not survive and his prison colony of a country would be turned to a sheet of glass, but he could always take out Seoul and Tokyo as he goes out in a blaze of glory.
Back in the 1980s when Ronald Reagan first proposed missile defense systems, it was somewhat about strategic advantage vis-a-vis the Soviets, but it was more urgently about the possibility that one day a lunatic would get his hands on nuclear weapons and would not be the least bit reticent about using them. Democrats scoffed at this, and for decades either blocked or dragged their feet on development of such systems. Today we're scrambling to get them ready, because the lunatic is in our midst:
