We have known for years that while previous US presidents saw alliances with other Western nations as mutually beneficial promoting their joint security and prosperity, Trump sees them as ripoffs.
Starmer will hope the meeting will secure Britain favours, while acutely aware those favours can be taken away equally quickly.
He threatens friends with swingeing tariffs for instance and demands the mineral riches of Ukraine - a country already broken by three years of war.
In Trump's world view, for one country to prosper another must lose.
For years American presidents have been urging Europeans to spend more on defence, in vain.
