From multiple senior defense officials:
The SA-11 system is very complicated and comprised of multiple parts, including radar, a launcher, and command vehicle. Officials here stress this is not something the average insurgent could fire without extensive training.
And officials here who have seen the latest intelligence all confirm this was a single shot fired from an SA-11 SAM in the Donetsk region of Ukraine.
It’s important to note that the SA-11 can be used as an autonomous system, operating with its own independent radar, but it can also find targets by tapping into a larger more sophisticated Integrated Air Defense system of, for example, the Russian military.
The working theory is still that separatists fired the missile while mistakenly thinking they were targeting a Ukrainian military aircraft.