Sir Keir Starmer confirmed he is prepared to put a peacekeeping force into Ukraine if there is a deal to end the war with Russia, acknowledging this could put British troops “in harm’s way” if Russian President Vladimir Putin attacks again.

The Prime Minister is joining European leaders for emergency talks in Paris as they scramble for a strategy in response to US President Donald Trump’s push for a deal with Russia and fears the US will reduce its defence commitments in the continent.

Sir Keir said the crisis was a “once in a generation moment” and an “existential” question for Europe.

Writing in The Daily Telegraph, the Prime Minister said the UK was “ready to play a leading role” in Ukraine’s defence and security, including the commitment of £3 billion a year until 2030.

But he said that along with military aid to Ukraine “it also means being ready and willing to contribute to security guarantees to Ukraine by putting our own troops on the ground if necessary”.

“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,” Sir Keir said.

“But any role in helping to guarantee Ukraine’s security is helping to guarantee the security of our continent, and the security of this country.

“The end of this war, when it comes, cannot merely become a temporary pause before Putin attacks again.”