On March 29, the Syrian Defense Ministry released a video depicting clashes between government forces and the militant coalition led by Hayat Tahrir al-Sham (formerly Jabhat al-Nusra, the Syrian branch of al-Qaeda) in the northern counryside of Hama
The first seconds of the video allows to see a Russian-made TOS-1 heavy flame-thrower system firing at militant positions.
On March 25, SF reported that three TOS-1 heavy flame-thrower systems were sent from Tartus to Hama to assist government troops repelling the Hayat Tahrir al-Sham-led offfensive in the area.
It is not clear by whom TOS-1 systems are operated. But most likely, Syrian army crews operating these systems are advised by Russian military specialists.