All four of Moscow's airports including another about 100 miles southwest of the Russian capital were temporarily shut down for undisclosed security concerns, authorities said.

All four of Moscow’s airports were temporarily closed without any reason given, according to Russia’s aviation watchdog. ‘Aircraft crews, air traffic controllers and airport services are taking all necessary measures to ensure flight safety,

Russia's aviation authority announced the temporary closure of all Moscow airports and the Kaluga airport. The statement did not specify reasons but emphasized that crews and controllers are ensuring flight safety.

The authorities temporarily closed Moscow's four airports, citing safety reasons, but the restrictions were later lifted.

"To ensure the safety of civil aircraft flights, temporary restrictions have been introduced on the operation of Sheremetyevo, Domodedovo, Vnukovo, Zhukovsky and Kaluga airports," Rosaviatsiya said on Dec.