"According to multiple web sites (such as Engagement and Fire Control Radars (S-Band, X-band) ) the 9S35 Fire Dome radar mounted to the Telar in the Buk M1 system DOES have standalone IFF capabilities."
it does but its usage requires properly trained squad, at this point I wouldn't be surprised if rebels only knew how to acquire target and shoot and used their "spies" some hundreds miles to the west to alarm them about incoming military aircraft