In the latest issue of its monthly propaganda magazine, the Islamic State says it targeted the passenger plane in response to Russian airstrikes in Syria.
ISIS has now claimed responsibility for major terror attacks in France, Egypt and Lebanon. This could galvanize its enemies to take stronger action against the extremist group, some analysts say.
The Pentagon has not said whether it was able to kill the ISIS leader, whose real name is Mohammed Emwazi. He appeared in videotapes released online of Americans and other hostages being murdered.
The self-declared Islamic State has purportedly claimed responsibility for two blasts on a busy street. Lebanon's Health Ministry says the attack killed at least 40 people and injured 239 more.
The head of Syria's antiquities agency was in Italy making an appeal for help to stop the destruction of his war-torn country's cultural heritage at the hands of Islamic militants.
Prime Minister David Cameron also said the Islamic State may have been responsible. Russian and Egyptian authorities cast doubt on the claim saying the bomb theory was mere "speculation."
Defense Secretary Ashton Carter told the Senate Armed Services Committee that the U.S. would not hesitate to back its partners using airstrikes or "direct action on the ground."