He gave his permission, express or implied, to allow sophisticated BUK launchers to be delivered into rebel territory.
Hmm. I'd be very careful about arguing that the Head of Government of a country that supplies arms to one side or another in a conflict is personally responsible for what they are used for.
Next thing, we'll have POTUS and The Prime Minister hauled off to The Hague to stand trial for "civilian collateral damage" in <insert name of chosen conflict theatre>... People in glass houses...
Also, he surely knew about the other shoot downs in the days preceding MH17.
Shame that nugget of information, seemingly in the public domain, didn't find its way to the Ukrainian equivalent of the FAA/CAA or to Eurocontrol. Then someone might have closed the damned airspace and 298 people would going about their lawful business.
(Neither of those comments are intended to imply support for one side or the other, by the way. But using the deaths of innocents to make geopolitical hay while the sun shines doesn't exactly present an edifying spectacle, IMHO.)