Political and military leaders in Europe are fleshing out details of a plan for European forces to help ensure Moscow does not attack Ukraine again once the guns fall silent.

The Kremlin said on Thursday that any plan to send European troops to Ukraine as part of a potential peacekeeping mission would be unacceptable for Russia and that it was monitoring such proposals with concern.

In the shadow of imminent defeat, European powers have unveiled their most audacious military initiative since the end of World War II. As Russia tightens its grip on Ukraine, Britain and France are preparing to cross a line that could potentially reshape the continent's security landscape forever.