North Korea appeared to resume activities this year aimed at producing plutonium, which can be used in the core of an atomic bomb, the U.N. nuclear watchdog has confirmed, though it added that signs of those activities stopped last month.

Pyongyang vowed in 2013 to restart all nuclear facilities, including the main reactor at its Yongbyon site that had been shut down and has been at the heart of its weapons program.

It said last year that Yongbyon was operating and that it was working to improve the “quality and quantity” of its nuclear weapons. It has since carried out what is widely believed to have been its fourth nuclear test. Continue reading.