"Unknown saboteurs" have seriously damaged two planes and a helicopter at Chkalovsky Military Air Base in Moscow Oblast, Ukrainian military intelligence reported on Sept. 20.
According to military intelligence, Russia is investigating how saboteurs managed to enter the "closely guarded" airfield, which is 25 kilometers to the northeast of Russia's capital, and damage an AN-148 transport jet and an Il-20 surveillance aircraft.
A second AN-148 that was parked in the vicinity received "minor damage," military intelligence said.
One Mi-28N attack helicopter was also seriously damaged, military intelligence said, adding that this helicopter was "actively involved in shooting down attack drones over Moscow region."
The Russian authorities frequently claim that drones are shot down over Moscow Oblast.
On Aug. 30, Moscow Mayor Sergei Sobyanin claimed that Russian air defense had destroyed a drone bound for the city amid what he called a "massive" strike on Russia's western regions.
The same wave of drone strikes hit a military airfield in Pskov, destroying four Russian Il-76 aircraft.
Military intelligence chief Kyrylo Budanov said on Aug. 31 that the drone attack was launched from within Russian territory.