Sometimes when they want to be seen, Russian military will turn on their responder and show up on radar.
Very rare is it the plane (commercial) that fly into Syria or Iraq.
The radar (flightradar24) is fascinating. (traffic now over the ME)
https://www.flightradar24.com/35.32,51.68/4
Sure,,,I am sure that coalition forces are using transponders.
The Russian have them, but that’s not the error they are making..
They are ignoring the Turkish border and could have easily adjusted their tactics in a zone near that border.
Now Putin is threatening Turkey within only hours of the incident..
It’s all occurred before in differing era’s, and different minutia..
It’s just that history always repeats..and Russia also repeats it’s mistakes and it’s arrogance.