Ukraine staged a dramatic series of strikes across Russia, deploying drones hidden in trucks deep inside the country to hit strategic airfields as far away as eastern Siberia.

Around the same time, Moscow launched one of its longest drone and missile attacks against Kyiv, escalating tensions ahead of crucial peace talks this week.

More than 40 Russian aircraft, including the Tu-95 and Tu-22 M3 long-range bombers capable of deploying conventional and nuclear weapons, as well as the A-50, are reported to have been damaged in the operation on Sunday, an official in Ukraine’s Security Service said on condition of anonymity as the details are not public. Ukraine’s Security Service chief Vasyl Malyuk led the operation, and losses are assessed to be at least $2 billion, the person said.