Russia also said it would shut down its last plutonium-producing reactor.

ECONOMIST: Disarmament and counter-proliferation

North Korea was no doubt keen to keep promised oil flowing over the winter, but work to disable its plutonium-producing reactor at Yongbyon another of Mr Kim's six-party obligations has now slowed too.

ECONOMIST: Time for North Korea to come clean about its nuclear past

The light-water reactor, which is not capable of producing weapons-grade plutonium, was promised to North Korea in the early 1990s for the North giving up its nuclear weapons.

CNN: North Korea claims to have weaponized plutonium