Vox interviews Ash Carter: are the lines of military deterrence blurring?

Defense Secretary Ash Carter, as he comes into what could be his last year overseeing the most powerful military on Earth, has begun talking about something surprising: a return to great power competition. During a recent interview at the Pentagon, we asked Carter how he thought about navigating this new world, and he returned over and over to the same answer: deterrence.

But as the norms and tools of warfare are changing, how well does deterrence still work? Can this Cold War–era idea still keep the peace in a new era? Here's why this challenge has such high stakes for the world — and what Carter had to say about it: