It is well understood that Donald Trump is a transactional politician. He sees international affairs as a zero-sum game in which, if one country gains, another must lose. He wants America to gain, and expects other countries to lose, even if they have traditionally been America’s allies. He respects Vladimir Putin because he has invaded a neighbouring country and taken some of what he wants.
The temptation, when dealing with such a crude politician, is to find ways of telling him what he wants to hear. No doubt Sir Keir Starmer will be diplomatic. He can say that Mr Trump is right that European nations should bear more of the burden of the defence of their own continent. This was something that we all knew to be true, and it is unfortunate that we Europeans failed to act on it before the great bully arrived on the scene and forced us to act.