There was a SU25 shown near the commercial jet by Russian radar. And we have reports from aviation experts, not verified, that the Ukrainians were running CAP missions ever since they lost a fighter to the Russians.
We do not know exactly what happened yet, since the Ukraine will not release air traffic controller records or any of their air traffic radar records yet. Other then that, read post #15.
I’ve taught tactical application of radar countermeasures for 24 years, but if you saw it on Wiki then, yea, you’ve got to be right.