Decoding North Korea is not easy at the best of times. That in itself is a Pyongyang ploy. An aura of mystery and a reputation for unpredictability are useful: they keep the world guessing, and nervous of provoking such a maverick. Blood-curdling rhetoric too is par for the course; yet grows stale by repetition, making it hard to know when they really mean it. Brinkmanship, again, is a tried and tested tactic. Far from incompatible with a will to negotiate, North Korea tends to take a maximalist stance before entering talks – such that any slight concession from the extremes it has gone to is seized on with relief by its interlocutors, as a sign of progress.