British Prime Minister Keir Starmer said Sunday that the U.K, France and Ukraine have agreed to work together on a ceasefire plan.

“Even while Russia talks about peace, they are continuing their relentless aggression,” Starmer said at a summit on the war in Ukraine. 

Starmer said the agreed upon ceasefire plan would be presented to the U.S.

“We need to agree what steps come out of this meeting to deliver peace through strength for the benefit of all,” he said, according to the Associated Press. “So, let’s get started.”

He also said Britain is ready to put "boots on the ground and planes in the air" to defend Ukraine.

"Europe must do the heavy lifting," he said. "Let me be clear, we agree with Trump on the urgent need for a durable peace. Now we need to deliver together."