The United Kingdom would be “ready and willing” to deploy British troops in Ukraine as part of a potential peace deal, Prime Minister Sir Keir Starmer declared Sunday.

Europe is “facing a once-in-a-generation moment for the collective security of our continent,” Starmer warned in an article for The Telegraph, emphasizing the broader stakes of the conflict started by Russia nearly three years ago. “This is not only a question about the future of Ukraine – it is existential for Europe as a whole.”

The declaration marks a significant change in position from the U.K. on direct military involvement, and comes ahead of talks between Russia and the U.S. aimed at bringing an end to Vladimir Putin’s war—talks from which Kyiv has been excluded, according to Ukrainian officials.

This is a breaking news story and will be updated shortly.