U.S. intelligence officials have used satellite imagery, intercepted conversations and social media postings to present what they call a solid circumstantial case that the plane was brought down by a Russian-made SA-11 surface-to-air missile fired by Russian-backed separatists in Eastern Ukraine. [...] they have not offered proof that the separatists obtained the sophisticated missile system from the Russian government. [...] they say they have not determined what, if any, involvement Russian operatives may have had in directing or encouraging the attack, which they believe was a mistaken attempt to hit a Ukrainian military aircraft.