How serious is the North Korean nuclear threat?

By his own standards, Kim Jong Un has had a good year. At the start of 2017, the Supreme Leader announced North Korea had entered "the final stage of preparation" to test launch an intercontinental ballistic missile. He kept his word and, three such tests later, he declared last month that North Korea has "finally realised" its dream of being a state nuclear force. Observers expect him to say in his coming new year's address he has completed the nuclear weapons programme that underpins his leadership.

But although Pyongyang has launched its longest range missile to date and conducted its sixth nuclear test this year — a possible hydrogen bomb — the US is not so sure. US military planners already assume North Korea can land a missile in the US but intelligence assessments vary and defence secretary Jim Mattis says North Korea is still "not yet" a capable threat to the US.