Trump and North Korea: the perils of a pre-emptive strike

Days before his inauguration, Donald Trump dismissed the claim from North Korean leader Kim Jong Un that he would soon test an intercontinental ballistic missile. “It won’t happen,” Mr Trump tweeted.

But over the past year Pyongyang has made big advances in being able to strike the US with a nuclear weapon. It has tested three intercontinental ballistic missiles and conducted a sixth nuclear test by detonating what may have been its first hydrogen bomb. The result has been a sharp escalation in talk about a US military response.

Just before Christmas, Jim Mattis, defence secretary, warned that “storm clouds are gathering”. General HR McMaster, the adviser who has been the most bellicose of the Trump national security team, says it would be “intolerable” for North Korea to be able to attack the US with a nuclear weapon. After Pyongyang in November tested a rocket with the range to reach anywhere in the continental US, he said the odds of war were “increasing every day”.

Governments around the world are trying to ascertain if the rhetoric is designed to underpin diplomatic efforts, or if Mr Trump genuinely believes Mr Kim cannot be deterred from using nuclear weapons and, therefore, is serious about preventing him from crossing the finishing line.