Israel felt threatened by its neighbors, so it not only bombed supposed Iraqi and Syrian nuclear sites, but also, with the clandestine help of other nations, developed its own nuclear arsenal to deter future attacks. For that, the U.S. understands and supports Israel.
North Korea, carpet-bombed by the U.S. Air Force from 1950 to 1953, bombings which killed more than 2 million people, mostly civilians; and which is now nearly surrounded by forces of the nuclear-armed U.S. (which had already nuclear-bombed two Asian cities in 1945) and has been threatened since 1953 by U.S. and South Korean military maneuvers nears its border and coastlines, attempts to develop its own nuclear deterrent, and the U.S. then threatens it with “fire and fury”.
So only nations acceptable to the imperialist U.S. are allowed to have a nuclear deterrent against annihilation. Any others MUST be threatened with annihilation by the “exceptional” and “indispensable” self-appointed guardian of freedom and democracy.