An SA-11 'Buk' missile fired from separatist-controlled territory in eastern Ukraine was responsible for the downing of flight MH17, the United States believes.
A statement from the US Embassy in Kiev read: "Over the past month, we have detected an increasing amount of heavy weaponry to separatist fighters crossing the border from Russia into Ukraine."
"We also have information indicating that Russia is providing training to separatist fighters at a facility in southwest Russia, and this effort included training on air defense systems."
The statement added that information - including social media posts by separatists and intercepted phone communications - indicated that separatists had claimed responsibility for the attack.
Thousands of online users have taken to social media to call for the victims of the Malaysian airliner crash to be returned to loved ones.
United States intelligence officials admitted that they do not know who fired the surface-to-air missile that downed flight MH17.
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