Every time North Korea needles the US with another provocation, it makes it harder for Donald Trump to mobilise the domestic support for a return to the negotiating table.
North Korea is a major military threat to the US and its Asian allies, but exactly how powerful are its nuclear weapons? An earth scientist explains why it's hard to answer this question.
Earthquakes can shape political decisions so understanding them is crucial.
Trump and Kim are due to meet this spring. But if these talks fail could international arbitration provide - as it has in the past - an alternative way out of the North Korean crisis?