Ukraine has launched a large-scale drone attack on military airfields in Russia, hitting and damaging at least two as it wages a ground assault inside the country that has rattled the Kremlin and altered the narrative of the war.

The Ukrainian General Staff reported the strikes on Wednesday night, saying that drones hit four airfields deep inside Russian territory. While the assault was the latest in a series of Ukrainian drone strikes on Russian air bases far from the front lines, analysts say it appeared to be one of the largest yet.

In particular, the strikes targeted airfields near Russia’s Kursk region, where Kyiv’s troops punched across the border in a surprise attack last week and have been advancing ever since.

Russia’s Defense Ministry said on Wednesday that Ukraine had launched 117 drones on multiple Russian regions, including those housing the airfields. It did not mention any damage. However, satellite imagery verified by The New York Times showed that Russian air bases in Savasleyka and Borisoglebsk, located 400 and 150 miles from the border with Ukraine, respectively, sustained damage.

Satellite imagery showed that the strikes destroyed at least two hangars and damaged a warehouse. It was unclear if any aircraft were hit. Images from the two other airfields that Ukraine’s military claimed it had hit did not show major destruction.

Ukraine has taken to targeting Russian airfields in hopes of crippling Moscow’s ability to launch devastating airstrikes against Ukrainian troops and cities.