But the official stressed a formal conclusion has not been reached by the U.S. intelligence community.

“There is a definite feeling it was an explosive device planted in luggage or somewhere on the plane,” the official, who is familiar with the latest U.S. intelligence analysis of the crash, told CNN.

Other U.S. officials also told CNN that the analysis is pointing toward the cause being a bomb.

Based on the same intelligence, the U.S. belief is that ISIS or an ISIS-affiliated group is responsible for the attack, the official said.