While all things in North Korea are cloaked in secrecy, it appears that this new reactor could produce material for nuclear weapons – potentially expanding North Korea's small stockpile.
Many Korea watchers speculated that once joint military drills ended, so would increased tensions with North Korea. But at least one analyst says this might be the moment the North lashes out again.
The last tangible thread of cooperation between Pyongyang and Seoul was cut today, with South Korea announcing it would pull the remaining workers from a sprawling factory complex in the North.
North Korea nuclear talks are possible if the North gives up its nuclear program, Secretary of State John Kerry said this weekend. That's not new, but Kerry's tone has worried some analysts.