The G7 summit takes place this weekend in Quebec, with much talk, none of it humorous, about needing to rename it the G6+1 or the G7-1 in recognition of the fact that this promises to be a showdown between the US President and every other world leader, not least America’s traditional allies including the UK, the host, Canada and France, represented by Mr Trump’s new friend, Emmanuel Macron.
And the reason is Mr Trump’s imposition of tariffs on his trading partners, a radical and alarming departure from the norms of international trade.
Matters have not been improved by Mr Trump’s series of provocative tweets, nor the fact he will be leaving the summit early, for his other important foreign engagement, on North Korea.
Naturally, the other six members of the group are preparing to make their feelings known.
Equally obviously, they must take on board the fact that they cannot afford to aggravate a conflict that turns into a full-blown trade war with a nation that accounts for more than half of the G7’s combined GDP.
The US is in a position of strength and the President knows it.
Mr Trump will be having separate talks with the Canadian and French leaders, though not with the Prime Minister, and later in Washington with the Japanese prime minister.
What they must make clear is that the art of the deal does not necessarily preclude a win for both parties, that free trade is to the benefit of all who engage in it.
The US trade deficit in crucial areas is not because of unfair trade rules and will not be remedied by tariffs.
It’s worth remembering that while a trade war and stand-off between the US and its traditional allies bode no good for either of them, there are potential winners in all this: they are Russia and China.
Mr Trump may like to reflect on this.