While, Pravda.ru’s report intimates that “Russia Closes Airspace above Syrian Coast”, there is however no official confirmation from the Russian Ministry of Defense other than a routine advisory pertaining to the conduct of war games off the Syrian coastline. According to Pravda.ru:
The message contains coordinates of the closed area and states the fact of firing exercises. The area of the exercises located in international waters of the Mediterranean is adjacent to the sea border of Syria. It will be closed on April 11-12, April 17-19 and on April 25-26 from 10 to 18 Moscow time.
Russia currently has about 15 warships and logistics vessels of the Black Fleet in the Mediterranean Sea, including Admiral Grigorovich and Admiral Essen frigates (they carry Caliber cruise missiles), as well as submarines.
These war games are conducted in response to ongoing US military threats directed against Syria, not to mention the ongoing deployment of US naval power in the Eastern Mediterranean.
It is also worth noting that according to the Daily Star (April 6, 2018) Russian warships have also been conducting naval war games in the Baltic Sea off the coast of Latvia. See screenshot below