The American government and media are loudly proclaiming that it must have been the Russian loyalists within Ukraine who shot down the plane because they possessed the type of missile used in the attack: SA-11 missiles fired from a Buk missile system.
Of course, the Ukrainians possess them as well. As the New York Times notes:
Ukrainian and American officials have accused Russia of providing the separatists with many sophisticated and powerful weapons, and the rebels have also captured many Ukrainian weapons, meaning they could have obtained SA-11s from either source.The pro-Russian “rebels” couldn’t have captured SA-11s from the Ukrainians if the Ukrainians didn’t have them first. Indeed, here is one of the military installations which has or had SA-11s and Buks .... http://investmentwatchblog.com