An Antonov AN-26 was shot down at 21,000ft on July 14. Assuming that the Ukrainians don't shoot down their own military aircraft, it was either shot down by the rebels or, possibly, the Russians. The rebels took credit and there is no real evidence that the Russians did it, AFAIK. Also, the twitter comments by the rebels immediately after MH17 crashed, and the conversation between rebel commanders released by the Ukrainians, speak against direct Russian involvement. (And on top of that, although militaries certainly do make big mistakes from time to time, it is clearly more likely that the poorly trained rebels would have made a huge fuck up like this than that the Russian military would have done so.)