North Korea was definitely the original gangster of nuclear proliferation. But now it freaks us out more about the size of its atomic arsenal than the fact it has nukes.

The North Koreans are not backing down, International Atomic Energy Agency chief Rafael Grossi tells Ian Bremmer on GZERO World.

Grossi recently visited South Korea, where he discussed the North's plans to acquire more nuclear weapons. He says that although North Korea kicked out IAEA inspectors in 2009, he has a pretty good idea of what Pyongyang is up to.