UPDATE: Having failed absymally with their earlier release of "information," US intelligence officials have tried to give more information... sadly this does not include any actual evidence, just statements and confirmation of YouTube clips...

Via WaPo,

Senior U.S. intelligence officials cited sensors that traced the path of the missile, shrapnel markings on the downed aircraft, voiceprint analysis of separatists claiming credit for the strike, and a flood of photos and other data from social media sites.

The officials also for the first time identified a sprawling Russian military installation near the city of Rostov as the main conduit of Russian support to separatists in Ukraine, describing it as a hub of training and weapons that has expanded dramatically over the past month. The officials said that tanks, rocket launchers and other arms have continued to flow into Ukraine

...

Senior U.S. intelligence officials said they have ruled out the possibility that Ukrainian forces were responsible for the attack.

“That is not a plausible scenario,” said one senior U.S. official, who noted that American intelligence agencies have confirmed that Ukraine had no anti-aircraft missile system within range of the Malaysian flight at the time it was struck.

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The official was one of three senior U.S. intelligence officials who spoke on condition of anonymity during a briefing arranged for reporters in Washington

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“We are seeing a full-court press by the Russian government to instruct affiliated or friendly elements to manipulate the media environment to spread Russia’s version of the story,” the official said. “What this looks like again is a classic case of blaming the victims.”

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The officials also declined to provide more details on the satellites and other sophisticated sensors that enabled them to trace the path of the missile, citing concerns about compromising secret U.S. capabilities.

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The U.S. officials said they have confirmed the authenticity of some of those recordings, including one in which the self-proclaimed defense minister of the Donetsk People’s Republic, Igor Strelkov, claimed responsibility for shooting down a military transport plane at the time the Malaysian aircraft was struck.

Analysis comparing that audio clip to other confirmed recordings of Strelkov’s voice “confirmed these were authentic conversations,” one of the officials said.

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“If you listen to Youtube you get that: ‘we’re finding civilians,’” a senior U.S. intelligence official said. Partly for that reason, the official said, “the most plausible explanation to me is [it was] a mistake.”