North Korea is building nuclear missiles with which it could very soon be able to reach the continental United States. North Korea must be stopped.

If not, then Americans will be living under the threat that North Korea might actually launch a nuclear attack on our shores, potentially inflicting damage and death on a scale that could dwarf the horrors of Sept. 11, 2001, or Pearl Harbor. Any such attack could be suicidal for North Korea, inviting massive U.S. retaliation. But given North Korea’s long record of surprise attacks and utter disregard for civilized norms, it cannot be ruled out.

At the very least, North Korea will enjoy a vastly enhanced capacity for nuclear blackmail, able to extort concessions from the U.S., Japan and South Korea—which North Korea would like to subjugate under the banner of reunifying the Korean peninsula. North Korea’s example will further embolden other heavily militarized despotisms with interests hostile to the U.S., notably Russia, China and Iran. There is also the grave danger that North Korea will sell its nuclear wares to rogue states or terrorist groups.

The only real remedy is an end to the North Korean regime. Officially, the U.S. and South Korea have no appetite for such an endgame, fearing a replay of the bloody 1950-53 Korean War. The U.S. has pursued diplomatic solutions, via combinations of talks, deals, passivity, threats and sanctions. All have failed (repeatedly), while North Korea has become ever more dangerous. The big question, as yet unanswered, is: Now what?