"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.

Russia's aviation authority announced on Thursday the temporary closure of five airports, including all four Moscow airports and one in Kaluga, located 160km southwest of the capital. The aviation watchdog Rosaviatsia did not provide a reason for the closures.

Russia's point man for arms control cautioned Donald Trump's incoming administration against resuming nuclear testing, saying Moscow would keep its own options open.

Moscow has warned Donald Trump against resuming the testing of nuclear weapons when he takes office, saying it would “not rule anything out” in response to US aggression.

Andrii Yusov of Ukraine's Defense Intelligence said that Kyiv is increasing the range of its unmanned aerial vehicles.

Russia’s drone strikes on Ukraine have increased sixfold in four months. The offensive is being fueled by a facility in Russia’s southern Tatarstan region, which is ramping up production with the help of a low-skilled workforce of Russian students.