The prime minister's condemnation of Donald Trump's remarks about the war in Afghanistan are his strongest public criticisms of the president yet.
They come in a week where circumstances have led Sir Keir Starmer to conclude three times that it was necessary to publicly rebuke a man he has ploughed so much effort into building a strong relationship with.
I am told Sir Keir, on returning to Downing Street on Friday afternoon, saw it as essential to make his views clear in the most direct terms.
His tone and body language conveyed his anger, as did his words, in which he said what President Trump had said was "insulting and frankly appalling".
The president had claimed that the Nato defence alliance, of which the UK is a member, had sent "some troops" to Afghanistan, but they "stayed a little back, a little off the front lines."
