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

Under this approach, you build a reactor in plain sight, start producing plutonium, and wait for the U.S. to offer a deal.

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