The Fallout from the Iran Nuclear Deal has major implications for North Korea's nuclear program as well. It was just after announcing that the U.S. would cancel the Iran deal that Kim Jong Un of North Korea found himself back in China talking with China's leader who of course is a big ally of Iran, imports most of its oil from Iran and has large stakes in Iran's nuclear program and weapons program.
The Diplomat Magazine online has a good article explaining the connections between Iran's nuclear program and North Korea's.
I will add here that the Chinese telecommunications giant ZTE that has been in the news and came under stiff penalties for breaking sanctions law, was guilty of selling and transporting telecommunications equipment with U.S. technology to both North Korea and Iran at the same time 283 times! That's not a mistake, that's intentional. Hence the big controversy over ZTE in the past few weeks.