Donald Trump and Sir Keir Starmer struck up an unlikely bromance in the Oval Office on Thursday. 

The two leaders insisted the Special Relationship was alive and well despite tensions over Ukraine, with Mr Trump saying there was a 'very good chance' the two countries could agree to a trade deal that would be 'terrific for both'.

In an extraordinary 30-minute exchange at the White House, the President and Prime Minister lavished each other with praise and played down the vast political gulf between them.

Sir Keir set the tone for the Oval Office love-in by theatrically producing a letter from the King inviting the royal-loving President for an unprecedented second state visit. Mr Trump immediately accepted the invitation and offered Sir Keir a lifeline on several key political issues.

The President hinted that the PM was close to persuading him to exclude the UK from damaging tariffs being slapped on goods from China, the EU and Canada.

Asked if Sir Keir had convinced him, Mr Trump said: 'He tried. He was working hard I'll tell you that – he earnt whatever the hell they pay him over there.

'I think there's a very good chance that in the case of these two great, friendly countries we could very well end up with a real trade deal where the tariffs wouldn't be necessary.'

The two men gave little detail of what a trade agreement might involve. But Sir Keir suggested it would be focused on technology and predicted that collaboration between the two countries on AI could deliver a 'moonshot' such as curing cancer.

Mr Trump also indicated he will not veto Sir Keir's controversial plan to hand the Chagos Islands to Mauritius.

But Sir Keir failed to get the comprehensive US security 'backstop' he is seeking before committing thousands of British troops to keep the peace in Ukraine if a truce is agreed.

The PM told Mr Trump that American might was needed to guarantee a 'lasting peace'. But the President was ambiguous about what, if anything, he was willing to provide. He said the British 'don't need help' militarily and suggested that Vladimir Putin could be trusted to stick to the terms of any peace deal.

Pushed on whether the US would intervene if Russian forces attacked British troops, he added: 'I've always cared about the British. They don't need much help… They can take care of themselves…'

On a critical day for the Western alliance:

• Mr Trump said for the first time he wants to get 'land back' for Ukraine as part of any peace deal;
• Ukraine president Volodymyr Zelensky will visit the White House today to sign a deal handing America the rights to a huge chunk of his country's rare minerals;
• The US President said Britain had done 'the right thing' in leaving the EU, adding: 'It will work itself out, I think it's already worked itself out';
• He played down his controversial description of Mr Zelensky as a 'dictator', saying: 'Did I say that? I can't believe I said that';
• Sir Keir insisted free speech was not in retreat in the UK after Vice-President J D Vance repeated his warning that the UK was losing its traditional values.

The President was delighted with the letter from King Charles inviting him to Balmoral to discuss a second state visit. He described the King as 'a beautiful man', adding: 'And the United Kingdom is a wonderful country that I know very well.'

In opposition, Labour was fiercely critical of President Trump, with Foreign Secretary David Lammy branding him a 'tyrant in a toupee'. But Mr Trump insisted he and the PM 'get along very famously, as you would say', adding that he was a 'special man'.

Asked what the two men, who have starkly different political backgrounds, have in common, Mr Trump said: 'He loves our country and so do I – that's our common theme.'

The US President also paid tribute to Sir Keir's wife Victoria, who is not on the trip.

Discussing his relationship with the PM, he said: 'We have just a great relationship. We actually had a good relationship before. We've met a couple of times and I'm very impressed with him, and very impressed with his wife.

'I must say, she's a beautiful, great woman.' The Prime Minister intervened, placing a hand on the President's shoulder and saying: 'I second that.'

But Mr Trump's comments on Ukraine fell short of what the PM was looking for.

Ahead of the trip, Sir Keir warned that Putin would 'come again' unless the US provides a comprehensive security backstop. But Mr Trump rejected the idea, saying the Russian despot could be trusted to keep his word.

'I've known him for a long time now and I don't believe he's going to violate his word,' he said. 'I think the deal's going to hold.'

Asked about the need for US military involvement in a security backstop, he suggested the presence of American citizens working on the rare minerals deal would be sufficient deterrent.

He added: 'Well, there is a backstop. First you have European countries, because they're right there, we're very far away, we have an ocean between us. But we want to make sure it works. So I don't know whether you say backstop you mean a backstop psychologically, militarily or what.

'We are a backstop because we'll be over there, we'll be working in the country. That's a great thing economically for them because… we're going to have a lot of people over there… so I just don't think you're going to have a problem.'

The President did not rule out tariffs on the UK, but said he had a 'warm spot' for the country and would have a 'good discussion' about it with Britain.

The White House welcomed Sir Keir's decision this week to raise defence spending to 2.5 per cent GDP and his 'leadership' in offering to send troops to Ukraine – but urged him to go further.

A senior Trump administration official said: 'President Trump does continue to urge our Nato allies to increase their spending even further towards 5 per cent.'