US faces intel hurdles in downing of airliner
U.S. officials are loathe to discuss the fruits of the National Security Agency's formidable eavesdropping capabilities, so it's not known whether the NSA picked up any conversations among Russian officials suggesting Russian complicity. Even if the agency had such evidence, officials would be unlikely to alert the Russians by revealing it publicly, one senior U.S. official said.
However, officials say, the Russian military and intelligence agencies are extremely disciplined and well aware of U.S. electronic monitoring, which makes them a tough target.
U.S. officials have not expanded in public on the case they made in a briefing to reporters Tuesday about the passenger jet.
But on Thursday, State Department spokeswoman Marie Harf said the U.S. has "new evidence that the Russians intend to deliver heavier and more powerful multiple rocket launchers to the separatist forces in Ukraine," and that "Russia is firing artillery from within Russia to attack Ukrainian military positions."
U.S. officials said the information came from satellites and other technical means, not human sources.