Ukrainian forces have destroyed dozens of Russian warplanes parked at airfields thousands of miles from the front lines, according to a source in the country’s security services, in one of Kyiv’s most audacious and sophisticated counter assaults since the beginning of the war.

Satellite photos analyzed by The Associated Press on Wednesday showed seven destroyed bombers on the tarmac at a Russian air base in eastern Siberia, one of the targets Ukraine said it struck with drones in one of the most daring covert operations of the war.

Sharing further details of the large-scale assault, Ukrainian officials said that cruise missiles and hundreds of drones were launched targeting Kyiv, Chernihiv, Lutsk and Ternopil.