No surprise that these guys are doing this. I'd be willing to bet that they have numerous other sites now online (it takes about 1-2 years from start to operational) since the "official" shutdown of the reactors some years ago. Combine the relatively short build time with around a 4-year enrichment calendar, I'd bet that Kim's game this time is with full knowledge that he has a shitton more nuclear material than the west suspects.

The restarting of Yonbyon is just a "make my day" move to try and goad an incident. If it were otherwise, NATO would have already begun to talk up plans to flatten the reactor.