He will also meet with President Emmanuel Macron, who has increasingly disagreed with Mr. Trump on issues like climate change and the nuclear accord with Iran.

That accord came up on Mr. Trump’s last day in Britain, when the president said in a television interview with Piers Morgan that he preferred talking over military action on Iran.

In Ireland: During his layover in the country, Mr. Trump predicted that Britain’s withdrawal from the E.U. would be good for Ireland “with your wall, your border.” The Irish prime minister, Leo Varadkar, replied that his country wanted to avoid “a wall or border” with Britain.

Go deeper: Mr. Trump has become an unlikely kingmaker in the race to become Britain’s next prime minister, with candidates competing for his favor.