Cautioning that he didn't want to draw conclusions until more information was available, McCain told MSNBC's Andrea Mitchell that there has been a pattern of pro-Russian forces already shooting down several Ukrainian aircraft.
"This was an airliner headed towards Russian air space," the Arizona Republican said. "And it has the earmarks -- and I'm not concluding -- but it has the earmarks of a mistaken identification of an aircraft that they may have believed was Ukrainian. If that's true, this is a horrible tragedy event which was certainly unanticipated by anybody, no matter who they are."
McCain added that the event had all the makings of a "tragic mistake" that would carry incalculable repercussions for those responsible.
"If it is the result of either separatist or Russian actions mistakenly believing that this was a Ukrainian war plane, I think there's going to be hell to pay," he said. "And there should be."