After the visit from Sir Keir, Trump will host Ukrainian President Volodymyr Zelensky.

Zelensky has said the deal on minerals is preliminary and that he still wants further agreements, arguing that without security guarantees from the US “we won’t have a ceasefire, nothing will work.”

Foreign Secretary David Lammy, speaking to ITV’s Peston programme, sounded hopeful about a deal.

“If US interests are on the ground in Ukraine, then that is the best security guarantee that the Ukrainians can have,” he said.

Sir Keir was notably guarded in his remarks in advance of Thursday’s meetings in the White House, such are the stakes and sensitivities around Ukraine, the Middle East and trade with America since Trump’s inauguration.

Strengthening and deepening the US-UK relationship might be his ambition, but it is far from guaranteed with such an unpredictable president.

But asked if he could trust Trump, given what he had said in recent weeks, the prime minister replied: “Yes, I’ve got a good relationship with him.

“As you know, I’ve met him, I’ve spoken to him on the phone, and this relationship between our two countries is a special relationship with a long history, forged as we fought wars together, as we traded together.”

Does he think President Trump sees Russia as the aggressor in Ukraine?

“Of course, the president has been very clear about the peace that he wants – he’s right about that.

“We all want peace – the question is, how do we make sure it’s a lasting peace.”

“There’s no issue between us on this,” Sir Keir insisted.

Theresa May, former prime minister and Conservative peer, urged Sir Keir to tell Trump that Russia is the aggressor in Ukraine.

Speaking in the House of Lords on Wednesday, she said: “Will he impress on President Trump that…the defence of Europe benefits the defence of America, and the Ukrainians are fighting for their independence and their sovereignty – principles which should be defended by all of us who value or benefit from economic and democratic freedom.”