Three days ago. Mortar?
17m17 minutes ago
Acc. to @kommersant , on 31 Dec 2017 at least 7 RuAF A/C - 4 Su-24M, 2 Su-35S and 1 An-72 - were destroyed at Hmeymim by rebel mortar fire:
EDIT part translate
As it became known “Kommersant”, December 31 on the base Hamim (the Syrian province of Latakia) was one of the most serious accidents in the two and a half years of conducting military air operations in Syria. According to “Kommersant”, the day the airbase came under a mortar attack by radical Islamists, owing to what was destroyed, at least four front-line bomber su-24, two multi-purpose fighter su-35S and one military transport aircraft An-72. Wounds could get more than ten soldiers.
About the emergency at Syrian airbase Hamim “b” has learned of two military-diplomatic sources. Without going into detail, they reported that one of the militants of terrorist groups shelled a Russian military facility in Syria, so that was actually destroyed four bombers su-24, two su-35S, one transport An-72 and an ammunition dump, sdetonirovala after being hit by a mortar shell. In total, according to unofficial data, could suffer more than ten soldiers. In the defense Ministry, the incident had no immediate comment on: the military only officially confirmed the death of two pilots who, in that day, a Russian helicopter Mi-24. According to the defense Ministry, no fire impact on the helicopter were not summed to the technique itself.
The incident in Mamimi can be considered one of the most serious for all time of operation in Syria.