This New Weapon from North Korea Could Kill Up to 90% of Americans

The threat of an EMP from a high-altitude nuclear detonation destroying the US has never gone away, and now it's taken on a new dimension with North Korea obtaining nukes and ICBMs:

http://bigthink.com/paul-ratner/congress-warned-this-new-weapon-from-north-korea-could-kill-up-to-90-percent-of-americans

Heavy research into anti-ICBM technology is probably the best overall deterrent, I would say.