A related article on Al Arabiya with speculation in the last line as to what it might have been. Again we must overlook some mystifying English.
"According to Maria Dubovikova, president of the Moscow based International Middle Eastern Studies Club, the timing of the attack is quite disturbing, as the Sochi congress in Syria has just passed.
"The Su-25 was targeted during his control flight around the de-escalation zone. De-escalation zones are considered the cornerstones of the peace process in Syria. The incident may pose one Russian retreat of forces from Syria," she said.
Dubovikova said that another possible source of MANPAD system might be the Ukrainians. "It's difficult to prove, but they are always active on black market; especially after the rupture with Russia. There are some rumors here in Russia that it was an Igla MANPAD (9k38) SA18 or Chinese analogue FN-6 ".
https://english.alarabiya.net/en/fea...ith-arms-.html