WASHINGTON, July 22 - The U.S. government believes that pro-Russian separatists most likely shot down a Malaysia Airlines jet "by mistake," not realizing it was a civilian passenger flight, U.S. intelligence officials said on Tuesday, Reuters reported.

The officials, who spoke on condition of anonymity, said the "most plausible explanation" for the destruction of the plane was that the separatists fired a Russian-made SA-11 missile at it after mistaking it for another kind of aircraft.