Sir Keir’s challenge is to engage with the US president on his own terms, while cajoling him towards a more sophisticated understanding of events – one that includes the concept of an ongoing US interest in Nato and the security of European democracies.
Sir Keir will also want to reinforce the message, delivered to the White House earlier this week by the French president, Emmanuel Macron, that Russia cannot be trusted to honour any deals that don’t include a significant deterrent against further aggression by Moscow.
Sir Keir has to be realistic about the new and dangerous character of US foreign policy, but realism doesn’t equate to cynical accommodation with Mr Trump’s caprice.
Mr Trump’s scorn for Nato comes from the view, shared to some degree by previous US administrations, that Europeans use the alliance to freeload on the Pentagon’s resources.
The prime minister must handle Donald Trump with tact, but without flinching from a duty to confront falsehoods in the president’s worldview.
