When an international summit breaks up early, the leaders’ lunch is cancelled and there is no progress to announce, it is fair to conclude that things have not gone well. So both diplomats and markets have reacted negatively to the failure of the US-North Korea summit to advance the goals of denuclearisation, and peace on the Korean peninsula.

The outcome of the meeting between Donald Trump and Kim Jong Un is undoubtedly a setback. But it is not a disaster. As Mr Trump suggested, it does not preclude the possibility that a deal will eventually be reached. Those with long memories might recall the 1986 Reykjavik summit between Ronald Reagan and Mikhail Gorbachev, the leaders of the US and the Soviet Union, which broke down in dramatic fashion — only to be followed by an arms control agreement a year later.

Mr Trump, like the late President Reagan, stands accused of going into a summit under-prepared and of placing too much emphasis on personal chemistry with his opposite number, rather than careful diplomatic preparation.