LONDON/PARIS — Britain and France are leading a multinational military exercise in Poland this month to test the deployment of a force to Ukraine should a peace deal with Russia be agreed, officials said.

Exercise Koalicja, running from November 9 to November 22, involves approximately 3,000 military personnel from 12 European nations and is the first major drill conducted by the Multinational Force Ukraine (MNF-U), the military arm of the Coalition of the Willing.

The exercise rehearses the movement of personnel, equipment and supplies, and tests command-and-control arrangements for a force that would help rebuild Ukraine's armed forces and secure its skies and seas once fighting ceases. Some 300 British troops, including soldiers from the Army's 7 Brigade (Desert Rats), and RAF Typhoons and a Voyager refuelling aircraft are participating.

The force would only move into Ukraine once fighting has ended and at the request of Ukraine's government, and would not conduct peacekeeping or ceasefire-monitoring duties. It would not be operating under NATO command or on the front line, and Western officials say the force would be able to defend itself if attacked.

Lieutenant General Tom Bateman, the UK commander of MNF-U, said the exercise was an important step in translating political commitments into credible military readiness. The 11 participating nations besides the UK are Belgium, Estonia, France, Germany, Lithuania, the Netherlands, Poland, Spain, Sweden and Türkiye. Turkish forces are standing up the MNF-U's maritime element in Istanbul, testing arrangements for maritime mine clearance.

Defence Secretary Wes Streeting said the exercise showed Britain, France and their allies were stepping up preparation for the day when peace came to Ukraine. "This is not a hypothetical plan, it's a real force, ready to help Ukraine once the fighting stops."

The UK jointly leads the MNF-U with France, with the force's headquarters set to move from Paris to London this year. The United States has been involved in discussions but is not contributing to the mission. Russia has voiced opposition to foreign troops being stationed in Ukraine, with President Vladimir Putin saying last year they would be "legitimate targets". Western officials have declined to spell out the rules of engagement if any international troops were to be attacked, though they say the force would be able to defend itself.