Starmer, a cautious center-left politician, has avoided directly contradicting Trump or criticizing his actions. The U.K. joined the U.S. in refusing to sign a joint declaration at an Artificial Intelligence summit hosted by Macron in Paris this month in what was seen as an attempt to curry favor with Washington.

French President Emmanuel Macron said on Thursday that Ukrainian President Volodymyr Zelenskiy was a "legitimate" leader and that, unlike Russian President Vladimir Putin, he had taken office through a free election process.