British Prime Minister Keir Starmer has warned that a deal on Ukraine cannot "reward the aggressor," as he met US President Donald Trump who has reached out to Russia.
"We have to win the peace, and that's what we must do now, because it can't be peace that rewards the aggressor or that gives encouragement to regimes like Iran," Mr Starmer told a joint news conference.
Mr Trump told the press conference that a peace deal needs to be struck soon between Ukraine and Russia, or it may not happen "at all".
"I think we've made a lot of progress and I think it's moving along pretty rapidly," Mr Trump said. "It'll either be fairly soon or it won't be at all."
Mr Starmer praised Mr Trump for his "personal commitment to bring peace" in Ukraine and said the UK is "ready to put boots on the ground and planes in the air to support a deal".
He said: "We're focused now on bringing an enduring end to the barbaric war in Ukraine. Mr President, I welcome your deep and personal commitment to bring peace and to stop the killing.
"We're determined to work together to deliver a good deal... that's backed by strength to stop Putin coming back for more"
"You've created a moment of tremendous opportunity to reach a historic peace deal. A deal that I think would be celebrated in Ukraine and around the world. That is the prize. But we have to get it right ... it can't be peace that rewards the aggressor or that gives encouragement to regimes like Iran.
"We agree history must be on the side of the peacemaker, not the invader.
"So, the stakes, they couldn't be higher.
"We're determined to work together to deliver a good deal. We've discussed a plan today to reach a peace that is tough and fair. That Ukraine will help shape. That's backed by strength to stop Putin coming back for more.
"I'm working closely with other European leaders on this and I'm clear that the UK is ready to put boots on the ground and planes in the air to support a deal. Working together with our allies, because that is the only way that peace will last."
Mr Trump praised Ukrainian President Volodymyr Zelensky as "very brave" and said he got along with him "really well", in a signal he was prepared to backtrack after calling the Ukrainian president a dictator.
Asked if he would apologise to Mr Zelensky for the remark, Mr Trump said: "I think we're going to have a very good meeting tomorrow morning. We're going to get along really well.
"I have a lot of respect for him."
He added: "We've given him a lot of equipment and a lot of money, but they have fought very bravely, no matter how you figure they have really fought. Somebody has to use that equipment and they have been very brave in that sense."
Minerals deal is security guarantee Kyiv need against Russia, Trump says
Ahead of their meeting, Mr Trump said that a minerals deal with Ukraine was the security guarantee Kyiv needs against Russia, brushing aside a plea from Mr Starmer for a commitment of more US military support.
Mr Starmer, who was meeting Trump at the White House for the first time since the US leader started his second term, turned on the charm, saying peace in Ukraine had only become possible because of Mr Trump.
In the Oval Office, Mr Starmer handed a letter of invitation from King Charles for a state visit, which Mr Trump accepted, however a date has not been set.
But underlying differences between the allies remained on the table for the private conversation that followed, including transatlantic frictions over US-Russia talks over the Ukraine war.
Before the meeting, Mr Starmer had argued that there could be no long-term peace in Ukraine without firm US security guarantees - an argument Mr Trump all but dismissed.
Asked if he could be persuaded to provide a backstop security position as part of a Ukraine peace settlement, he said: "President Zelensky is coming to see me on Friday, Friday morning, and we're going to be signing really a very important agreement for both sides, because it's really going to get us into that country."
He added: "It's a backstop, you could say, I don't think anybody's going to play around if we're there with a lot of workers and having to do with rare earths and other things which we need for our country.
"We appreciate it very much and I look forward to seeing him. We'll be talking about it and we'll also be talking about that today with the Prime Minister."
Mr Starmer is the latest European leader to meet Mr Trump after French President Emmanuel Macron came to the White House on Monday for a friendly encounter that nonetheless displayed stark differences about Russia's war with Ukraine and the US push for a quick ceasefire.
Mr Trump, who came into office on 20 January, has shocked traditional US allies in Europe by drawing closer to Mr Putin, calling Mr Zelensky a "dictator," and demanding payback for US financial support for Kyiv.
Mr Zelensky is expected to be in Washington tomorrow to sign an agreement with Mr Trump on rare earth minerals, a deal the Ukrainian leader said would hinge on further US aid.
Mr Trump portrays the deal as a way to recoup American money that has been spent to support Ukraine. It includes no specific security guarantees for Ukraine, a US official said.
Mr Starmer has signaled that Britain will increase defense spending and is expected to try to reassure the US president that Europe will provide support and security guarantees to Kyiv if peace talks with Russia are successful.
A senior Trump administration official told reporters they were pleased with Mr Starmer's pledges to increase defense spending.
Mr Putin warned "Western elites" against trying to sabotage a potential rapprochement between Russia and the United States, saying Moscow would use its diplomats and intelligence services to thwart such efforts.
The remarks were an apparent reference to the European Union and Britain.
Mr Trump has shattered foreign policy and domestic policy norms since the start of his second term, rattling allies by advocating for US ownership of Gaza and by promising trade tariffs on US friends and foes alike.
"We would want any economic relationship with the UK to be based on reciprocal and equal trade," the Trump aide said.
In the Oval Office, Mr Trump complained about trade relations with the European Union, which Britain left in 2020.
"On our trade, obviously, it is fair and balanced," Mr Starmer interjected, "and in fact you've got a bit of surplus so we're in a different position." The US has a trade surplus in goods with Britain, according to US government statistics.
Meanwhile, US Vice President JD Vance, who also attended the meeting, said the leaders would discuss what he described as "infringements on free speech" in Britain that have affected American technology companies.
"We've had free speech for a very, very long time in the United Kingdom," Mr Starmer responded.
Mr Trump's relationship with Mr Starmer got off to a friendly start in September with a two-hour dinner in New York at Trump Tower. The British leader's team said the atmosphere was warm with a "gracious host".
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Like Mr Macron, Mr Starmer will argue that a rushed peace deal with Russia, without the participation of Ukraine or European nations, might lead to further instability in Europe, which would not be good for the United States.
Mr Starmer has said he is open to British troops providing security guarantees to Ukraine but only alongside other European nations and with "the right conditions in place".
European countries are concerned about the high level of conflict in Ukraine now, the US official said, while a ceasefire would give them more comfort that their role is more about peacekeeping than deterring active conflict.
