The leaders of Britain and France are spearheading a desperate diplomatic drive to shore up Europe’s security, bolster Ukraine’s defenses and ensure the Trump administration doesn’t seek a ceasefire on terms that reward Moscow for invading its neighbor.

British Prime Minister Keir Starmer said Sunday Europe was at a crossroads in history and must do the heavy lifting to defend itself as world leaders met in London to discuss ways of working together to stop Russia’s war in Ukraine.