An alternative might be for the United States to draw a bright line, requiring verifiable information that a nuclear attack has occurred, before nuclear weapons would be used. Such a policy of No First Use, or NFU, of nuclear weapons has long been advocated by many prominent government officials and foreign policy analysts, both during and after the Cold War.
To be sure, this might undermine U.S. ability to respond to an imminent nuclear attack, including from a major power like Russia. But because it can so powerfully strike back, especially from its relatively invulnerable nuclear-armed submarine force, the United States could credibly promise to retaliate, even against a massive first strike, with devastating force.
What’s more, North Korea is unlikely to be able to hit the continental United States with nuclear weapons. Sure, it might strike vulnerable targets in South Korea, Japan or the Pacific region – but it would do so knowing it could be utterly destroyed in return. Even if North Korea could penetrate U.S. anti-missile defenses, its leaders would have to fear the incalculable damage and destruction from the U.S. response. It is inconceivable that a North Korean sneak nuclear attack could wipe out the U.S. ability to retaliate.