"The fact of use by militants of impactless unmanned aerial vehicles of aircraft type indicates that the militants have been transferred to technologies that allow carrying out terrorist acts using such unmanned aerial vehicles in any country", the military department of the Russian Federation said, reported Interfax.
It added that during the attacks on Friday night "no casualties or damage of property were reported by Russian military facilities".
A United States intelligence aircraft flew in the area between Khmeimim and Tartus during the attack on the Russian base in Khmeimim.
The attacks also raise questions about the sustainability of Russia's gains in Syria, said Jennifer Cafarella of the Washington-based Institute for the Study of War. Many opposition groups are refusing to attend, citing increased Russian military interference.
She said the incidents were proof that "whoever conducted these attacks can still penetrate regime areas and impose costs on the Russians".
Drones that attacked Russian bases in Syria last week were sent from Idlib, a "de-escalation" zone controlled by anti-Damascus fighters, the Russian defence ministry's official newspaper said Wednesday.More news: MoneyGram pilot is important real-world test for Ripple's payments plan
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In this connection the Russian Defense Ministry dispatched messages to the chief of the Turkish Armed Forces' General Staff Hulusi Akar and chief of the National Intelligence Organization Hakan Fidan. The Russian military denied that the attack damaged its aircraft.
The Syrian Observatory for Human Rights, a Britain-based war monitor, said the air strikes targeted Syrian army and Hezbollah weapon depots.
ISIS has also recently retaken portions of Idlib, despite Russian President Vladimir Putin's declaration of victory in Syria late previous year. The Defense Ministry said the solutions employed by the militants could have been obtained only from an industrialized country.
Explosives attached to drones used in an attack on Russian military bases in Syria.
The size of the Russian deployment in Syria is not known but independent Russian military expert Pavel Felgenhauer told AFP that up to 10,000 troops and private contractors could have taken part in the conflict.
The daring use of short-range mortars also pointed to the inability of Syrian forces to protect the Alawite heartland from hit-and-run raids by the rebels.