Expectations were not exactly high going into the weekend’s heads of government meeting of the Group of Seven advanced economies in Canada. The outcome, however, was worse than almost anyone could have imagined. In the end, it would have been better if President Donald Trump had carried out his threat and declined to attend the summit at all. As it was, he lashed out angrily at the countries that should be his allies, suggested that the grouping should expand to include a thuggish autocracy, and upped his threats of trade conflict to an even more extreme level.

By isolating himself so thoroughly, Mr Trump has firmly decided to make the G7 a G6 plus one. A forum that used to act as the steering committee for the world economy is now merely another theatre of combat for the president’s misguided trade war.

In truth, there is little else that the other G7 members could have done, or can now do, differently. Weeks of patient diplomacy from the other members of the group, particularly the Canadian hosts, to work Mr Trump round to the position of supporting at least in principle the need to resist trade protectionism failed.

Attempts to engage on the facts came to nothing. The president repeated again his delusions that the US is being cheated by its trading partners, including the bizarre accusation that the EU is a protectionist bloc that discriminates against American exports. As it happens, EU tariffs on average are about the same as those of the US.

Mr Trump clearly has no regard for the G7 as a club of advanced economy democracies. Instead, he broke with the consensus after the annexation of Crimea, and wanted to invite Russia back into the grouping. In effect, America under Mr Trump has gone rogue.