North Korea is an "illegal nuclear power" and has made substantial progress in its weapons development over the last decade, the head of the International Atomic Energy Agency (IAEA) said on Wednesday.

The comments, from Rafael Grossi, the new IAEA Director-General, come as Pyongyang has shown essentially no signs that it is willing to abandon its controversial nuclear weapons program -- even in the face of punishing global sanctions, occasional threats of war from the U.S., and, on better days, unprecedented diplomatic outreach from President Donald Trump.