Diplomacy is getting U.S. leaders nowhere in slowing the North Korean missile program, so now Washington will need to consider its military options. Beefing up missile defense of the homeland is much less dangerous than taking offensive action against North Korea. But all of the near-term defensive options for coping with the danger focus on one program: Ground-based Midcourse Defense (GMD). No other program in the Pentagon’s portfolio can intercept long-range ballistic missiles in the time frame when better defenses will be most urgently needed. So the Trump Administration needs to think in concrete terms about how to quickly make GMD as effective as possible. The most compelling options are increasing the number of interceptors above a planned 44; accelerating development of a redesigned kill vehicle to be carried on the interceptors; upgrading sensors used in discriminating hostile warheads from decoys and debris; building additional missile defense sites, perhaps with mobile launchers; and picking up the pace of testing to assure GMD would function successfully in a crisis. I have written a commentary for Forbes here.