European leaders met in London to formulate a plan to help end the war in Ukraine. But even potential peacekeepers face political and economic hurdles.

Ukrainian President Volodymyr Zelensky has said it would need an international force of up to 200,000 troops to sustain a ceasefire along the 600 mile (960km) line of contact between the two opposing armies, Russia and Ukraine.

Even as they have rallied to Volodymyr Zelenskiy's side after his Oval Office clash with Donald Trump, European leaders' approach to the war in Ukraine and the continent's security remains highly dependent on the U.