Buk surface-to-air missile system
They said the "most plausible explanation" for the shooting down of the plane was that rebels mistook it for another aircraft.
Evidence included images purportedly showing a surface-to-air missile launcher in the area, analysis of voice recordings of pro-Russian rebels apparently admitting bringing the airliner down and social-media activity pointing to rebel involvement.
The evidence also included satellite images of a facility allegedly used to train rebels near the Russian city of Rostov, which were later tweeted by Geoffrey Pyatt, US ambassador to Ukraine.