The pair met for further G20 summits in Argentina, in November 2018, and in Japan in June 2019.

John Bolton, Trump’s former national security adviser with whom he later fell out, was present on the latter occasion. He told the BBC he was struck by the men’s differing attitudes to detail, which he put down to Putin’s training in the Soviet intelligence service.

Of Putin, he said: “I’ve never seen him any way other than being prepared, very calm, very reasonable in his presentation, and I think that’s part of his KGB training.”

By contrast, Bolton said, Trump’s approach to private meetings was similar to his press conferences in public, in that he was prone to freewheeling statements that could surprise even his own aides. “He doesn’t really prepare for them because he doesn’t really think he needs to; he doesn’t think he needs the background information. I’m sure they’re preparing briefing materials as we always did, and he won’t read them.”

Trump believed that a healthy personal relationship with another leader would mean a healthy state-to-state relationship, Bolton said – and Putin knew this. “He will use his KGB training to try and manipulate Trump. He’s done it before and he’ll do it again.”

Trump himself has downplayed expectations ahead of Friday’s meeting in Alaska, remarking: “I think it’ll be good. But it might be bad.”