KYIV, Ukraine — The Russian military reported on Monday that it shot down a Ukrainian drone approaching an airbase deep inside Russia, the second time the airbase has been targeted this month, raising questions about the effectiveness of Russia’s air defenses if drones can fly that far into the country.

Russia’s Defense Ministry said the incident took place in the early hours of Monday, and three servicemen were killed by debris at the Engels airbase that houses the Tu-95 and Tu-160 nuclear-capable strategic bombers that have been involved in launching strikes on Ukraine.

Engels is located in Russia’s Saratov region on the Volga river, more than 600 kilometers (more than 370 miles) east of the border with Ukraine.

No damage was inflicted on Russian aircraft, the ministry said.

It is the second time Engels has been targeted by Ukrainian drones; on Dec. 5, unprecedented drone strikes on Engels and the Dyagilevo base in the Ryazan region in western Russia killed a total of three servicemen and wounded four more. The strikes on the airbases were followed by a massive retaliatory missile barrage in Ukraine that struck homes and buildings and killed civilians. (AP)