A pro-Russian fighter guards the crash site of a Malaysia Airlines jet near the village of Hrabove, eastern Ukraine, Saturday, July 19, 2014. Ukraine accused Russia on Saturday of helping separatist rebels destroy evidence at the crash site of a Malaysia Airlines plane shot down in rebel-held territory — a charge the rebels denied. AP Photo/Evgeniy Maloletka WASHINGTON (AP) — Senior U.S. intelligence officials say they have no evidence of direct Russian government involvement in the shooting down of Malaysia Airlines Flight 17.

They say the passenger jet was likely felled by an SA-11 surface-to-air missile fired by Russian-backed separatists in eastern Ukraine and that Russia "created the conditions" for the downing by arming the separatists.

The officials briefed reporters Tuesday under ground rules that their names not be used in discussing intelligence related to last week's air disaster, which killed 298 people.

They said they didn't know if any Russians were present at the missile launch, and they wouldn't say that the missile crew was trained in Russia.

A senior official said the most likely explanation was the plane was shot down by mistake.