THE leaders of the world’s most powerful nation and its worst rogue state have traded insults and threats for months. Yet quite suddenly there appears to be the possibility of rapprochement between the US and North Korea. Kim Jong-un, the North Korean dictator, has undertaken to suspend nuclear and ballistic missile tests and offered talks with the aim of giving up nuclear weapons. President Trump has responded by welcoming the “great progress being made” and agreeing to meet Kim by May.

It is, on the face of it, an extraordinary development. There is an unspoken convention of the presidency not to boast of the power of the country’s nuclear arsenal, yet that is what Trump did a few weeks ago when tweeting that his “nuclear button” was “much bigger (and) more powerful” than Kim’s. Given Trump’s mercurial instincts and the proven deceit and bellicosity of North Korea’s regime, a dose of scepticism is in order about what can be achieved in direct talks. Lacking diplomatic experience, Trump is liable to overestimate his powers of persuasion.

The danger is that Trump may end up giving concessions for no reason. The threat from North Korea long predates its nuclear adventurism. Kim’s grandfather, Kim II-sung, engaged in direct aggression (with Stalin’s agreement) in 1950, precipitating the Korean War. Any interim deal limiting North Korea’s nuclear programme should not be done at the price of US withdrawal or lifting sanctions. It would need intrusive verification measures to be credible. This is a test of Trump’s resolve.