Keir Starmer has issued a dire warning that Vladimir Putin will strike again if the US turns its back on Ukraine.

He will travel to Washington DC next week to tell Donald Trump that the “only way” to maintain peace in Europe is with an American safety guarantee. The PM joined alarmed European leaders at an emergency summit in Paris amid growing alarm over Trump’s interventions.

US and Russian officials will hold historic talks in Saudi Arabia about ending the war in Ukraine. But incredibly Ukrainian President Volodymyr Zelensky has not been invited – and neither have any European leaders. It has sparked alarm that the US will capitulate to Putin – made worse after Elon Musk heaped praise on the Kremlin delegation. It comes after Mr Starmer said he is prepared to put British boots on the ground in Ukraine if a peace deal is reached.

But he stopped short of criticising Trump, who he will meet at the White House next week.

In a strong message to the President he said a US security guarantee is the “only way” to stop Vladimir Putin‘s aggression. He demanded the US provides a security “backstop”, and said he would be taking this message to Washington DC next week.

The PM said Britain must take a “leading responsibility” in keeping the peace if a deal to end the fighting is agreed. The Prime Minister said: “Europe must play its role, and I’m prepared to consider committing British forces on the ground alongside others if there is a lasting peace agreement.

“But there must be a US backstop, because a US security guarantee is the only way to effectively deter Russia from attacking Ukraine again.”

Asked whether Trump had undermined the UK, Europe and Ukraine by opening peace talks without them, the PM swerved attacking the President.

European leaders and Ukraine are outraged they have been frozen out, following worrying signs the Trump administration will capitulate to Putin. Quizzed about the talks, the Prime Minister said: “What the United States wants is lasting peace, that’s what Ukraine wants, that’s what the United Kingdom wants and that’s what European allies want.

“What is important is that we ensure that Ukraine is in the strongest possible position, if we go into talks.” He added: “If there’s discussion about any guarantees that are being provided, that the European nations show willing, as I have done, but also are absolutely clear that it must be with a US backstop, because I don’t believe it will be a guarantee if there isn’t the US backstop behind those security guarantees.”

On Monday Mr Starmer said he was prepared to put boots on the ground in Ukraine to enforce a peace deal.

It is the first time a PM has made such a commitment since Putin’s invasion in 2022. At this stage other European countries have not done so – but are believed to be preparing for a peacekeeping mission.

Confirming that he would be prepared to send UK troops, the PM said: “I do not say that lightly. I feel very deeply the responsibility that comes with potentially putting British servicemen and women in harm’s way.”

But he reiterated that there must be US involvement, and that Britain would be part of a big operation. No10 refused to speculate how many servicemen and women would be sent.

A former British Army chief has warned the UK does not have the manpower or equipment for a lengthy peacekeeping operation in Ukraine.

Lord Richard Dannatt, who was chief of the general staff between 2006 and 2009, warned Keir Starmer that fulfilling his pledge will come at “considerable cost”. Lord Dannatt said: “Frankly, we haven’t got the numbers and we haven’t got the equipment to put a large force onto the ground for an extended period of time at the present moment.

“Now, if Keir Starmer wants to do that, that’s fine. The British Army will always stand up to the plate, but here we go again. We’ve got to have the right number of people with the right equipment and the right training, and start to fund that now.”

The Government has vowed to spend 2.5% of GDP on defence – but not said yet when that will be achieved. No10 said on Monday the results of a review will be released in the spring.

Potentially. Health Secretary Wes Streeting refused to rule out having to make tough decisions in order to ramp out defence spending, which currently stands at 2.3%.

There are concerns that some Government departments could face cuts of up to 11% to free up cash for the Ministry of Defence. Mr Streeting refused to say whether this would impact the Government being able to meet other pledges – such as cutting waiting lists.

He said: “There is no greater priority for any government, or any government worthy of the name, than the security of the nation. And as I say, the Prime Minister feels this very strongly too.”

A US and Russian delegation will meet in Saudi Arabia today to start discussing a possible peace deal.

Secretary of State Marco Rubio sat down with Russian Foreign Minister Sergei Lavrov at the Diriyah Palace in Riyadh. It comes after Trump and Putin spoke on the phone last week and announced they will start peace negotiations.

But it is feared the US will make a string of damaging concessions. Last week US Defence Secretary Pete Hegseth said it was not “realistic” for Ukraine to join NATO or return to its pre-2014 borders. It sparked a wave of criticism, with the Trump administration accused of capitulating to Putin.

Crucially Ukrainian President Volodymyr Zelensky said his country won’t accept the outcome if Kyiv doesn’t take part.

Trump’s close ally Elon Musk was fawning in his admiration for the Russians. He shared a photo of Lavrov and the Kremlin delegation landing in Saudi Arabia.

“This is what competent leadership looks like,” Musk wrote. It is another worrying sign that the US will not be playing hardball at any peace talks.

Emmanuel Macron, who called the emergency summit in Paris on Monday, warned against “capitulation”. It came after Trump suggested Russia might not make any concessions.

Mr Macron said a “peace that is a capitulation” would be “bad news for everyone”. He told the Financial Times: “The only question at this stage is whether President Putin is genuinely, sustainably and credibly willing to agree to a ceasefire on this basis. After that, it’s up to the Ukrainians to negotiate with Russia.”

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