David Sanger knows a thing or two about national security. After all, it's his beat at the New York Times.

So what does he think is the biggest threat to America's national security right now?

An "insider threat" to the stability of the election system coming not from Russia, not from China, and not from North Korea. The biggest menace is Americans willing to engage in political violence, Sanger tells Ian Bremmer on GZERO World.