WASHINGTON (CBS News) -- We are no closer to finding out who fired the sophisticated missile that blasted Malaysia Airlines Flight 17 out of the sky as the Boeing 777 cruised 6 miles above the war in eastern Ukraine.
Russia supports the Ukrainian rebels. U.S. intelligence said Tuesday it's most likely that those rebels fired a Russian-supplied missile at what they thought was a warplane.
The evidence presented by senior intelligence officials consists in part of pictures posted on social media. They show an SA-11 surface-to-air missile launcher, also known as a Buk, driving through rebel-controlled areas of Ukraine in the days before the shoot-down.
U.S. intelligence did not take the pictures and cannot independently verify them. But it can confirm the authenticity of phone calls intercepted by Ukrainian intelligence in which rebels are talking about positioning the SA-11.
The senior intelligence officials say the SA-11 likely came from a base in southwestern Russia as part of a buildup of rebel forces in recent weeks after they had suffered setbacks at the hands of the Ukrainian military.
U.S. intelligence was not aware of the SA-11 until the day of the shoot-down, when it detected a surface-to-air missile launch at the same time the airliner disappeared from radar. Photos of the wreckage show pitting the intelligence officials said was consistent with shrapnel from an exploding warhead.
Shortly after, a known rebel leader was overheard reporting, "We have just shot down a plane," although he did not know yet it was a civilian airliner.
The next day video of an SA-11 launcher missing one of its missiles and loaded on the back of a flatbed truck appeared on social media. It was supposedly taken near the border with Russia as the missile launcher was being shipped back to Russia.
One intelligence official called it a "solid case" that Russia provided the missile the rebels used to shoot down the airliner. But it is not an airtight case. Among other things, the official said, "We do not know who pulled the trigger."
For his part, Russian President Vladimir Putin said Tuesday that Russia will do "everything in its power" to cooperate with the investigation. But during a meeting with his security council, Putin again blamed Ukraine's government for the fighting in the east.
In Washington, President Barack Obama stopped by the Netherlands' embassy and signed a condolence book. He vowed the U.S. will not rest until justice is done.
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