The missile launched was of course used in conjunction with radar. There's very little to no chance that the pro-Russian separatists knew what type of plane they were taking down. The plane was presumed a threat, and the decision was made to eliminate it.
The takedown of 2 non civilian planes in recent days likely strengthened their presumption that the MH17 was a threat, and not a civilian plane.
Of course, there's still some conjecture floating around at these early stages of investigation.
In any case, the pro-Russian militia need to accept responsibility for their seriously detrimental actions.
The whole thing is a messy...
The Russian government was allegedly quick to blame the Ukraine for the incident, probably using existing problems there as ammunition, and the fact that the shoot down was in Ukraine airspace. It's no secret why the Ukraine is having problems though, and President Putin is hardly an innocent in that respect.
Will be interesting to see if Putin will be allowed to visit Australia in the weeks ahead. Doesn't look good for him ATM.
Politics aside, man I feel devastated for all those lost souls, and their families. Absolutely tragic.