The same cannot be said, however, for the U.S. troops stationed in South Korea and Japan. Those tripwire forces have become little more than nuclear hostages, well within range of North Korea's current missile fleet. Keeping the troops in such a vulnerable location is foolhardy.

Ironically, their presence may even reduce the credibility of the U.S. security commitment to the East Asian allies—contrary to the conventional wisdom about the effect of such deployments. The rationale for stationing tripwire forces in both East Asia and Europe during the Cold War was that the move guaranteed U.S. involvement in any conflict that broke out. Christopher Layne, the Robert M. Gates Chair in Intelligence and National Security at Texas A&M University's George Bush School of Government and Public Service, points out in his crucial history of the Cold War, Peace of Illusions, that U.S. allies repeatedly sought those deployments precisely for that purpose. Successive presidential administrations obliged, believing that the step was essential to reassure Washington's security partners that America would never, indeed could never, renege on its promises.