The UK and France have signed a declaration of intent on deploying troops in Ukraine if a peace deal is made with Russia, UK Prime Minister Sir Keir Starmer has said.
After talks with Ukraine's allies in Paris, he said the UK and France would establish military hubs across Ukraine and build protected facilities for weapons and military equipment to deter future invasion.
The agreement also proposed that the US would take the lead in monitoring a ceasefire.
Russia has repeatedly warned that any foreign troops in Ukraine would be a legitimate target, but has not yet commented on the announcement.
Russian President Vladimir Putin launched a full-scale invasion of Ukraine in February 2022, and Moscow currently controls about 20% of Ukrainian territory.
Heads of state and top officials from the Coalition of the Willing took part in Tuesday's talks in the French capital.
Speaking at a joint press conference after the meeting, Starmer said: We signed a declaration of intent on the deployment of forces to Ukraine in the event of a peace deal.
This is a vital part of our commitment to stand with Ukraine for the long-term.
It paves the way for the legal framework under which British, French, and partner forces could operate on Ukrainian soil, securing Ukraine's skies and seas, and regenerating Ukraine's armed forces for the future,
The UK prime minister added London would participate in any US-led verification of a potential ceasefire.
Top US negotiator Steve Witkoff said durable security guarantees and robust prosperity commitments are essential to a lasting peace in Ukraine - referring to a key demand made by Kyiv.
Meanwhile, French President Emmanuel Macron said Ukraine's allies had made considerable progress at the talks.
He said robust security guarantees for Kyiv had been agreed in the event of a potential ceasefire.
Ukrainian President Volodymyr Zelensky said a huge step forward had been made in Paris but added that he would only consider efforts to be enough if they resulted in the end of the war.
Territory and security guarantees have been at the forefront of unresolved issues for negotiators.
The original US-led 28-point peace plan widely leaked to the media last year was seen by Kyiv and its European allies as being heavily skewed in Russia's favour.
Last month, Kyiv sent the US an updated 20-point plan, as well as separate documents outlining potential security guarantees and provisions for Ukraine's reconstruction, Zelensky said.
