The FBI warning members of the U.S. military that ISIS is calling for attacks against them, saying "overseas based individuals are looking for like-minded individuals in the U.S. to carry out these attacks."
The new FBI bulletin goes on to say "We also request members of the military review their online social media presence for any information that might attract the attention of violent extremists."
Officials fear copycat attacks similar to those against Canadian military members - including the October 22nd shooting in Ottawa.
Republican Congressman Peter King is OutFront. He sits on both the Homeland Security and Intelligence Committees.
President Obama is ordering a review of how the U.S. handles terrorist-related hostage cases.
The big development comes as ISIS released video of its murder of American aid worker Peter Kassig, the fifth western hostage killed by ISIS since August.
The White House was quick to point out that paying ransoms is not on the table.
OutFront: Retired Air Force General Michael Hayden, who served as both director of the CIA and the National Security Agency.
American aid worker and former U.S. soldier Peter Kassig has been beheaded by ISIS terrorists. Kassig first went to the Middle East after he joined the U.S. Army in 2006.
He was briefly deployed to Iraq a year later.
But he returned in 2012 on his own, to deliver humanitarian aid to Syrians affected by the fighting there.
In an interview with CNN's Erin Burnett, Sarah Pollom, a friend of Kassig's, says his mission in life was to make a difference.
Earlier this week, Iraqi intelligence said Abu Bakr al-Baghdadi was dead or wounded from an airstrike. On Thursday, new audio on an ISIS social media account claims to be of the reclusive ISIS leader.
If this latest audio is genuine, it appears to disprove reports that Baghdadi was killed last Friday.
In the 17-minute speech, distributed over jihadi websites, Baghdadi makes reference to events that happened after he was supposedly killed or seriously wounded.
Officials are now pouring over the new audio tape, trying to determine if Baghdadi is in fact still alive, where he is, and what he might be planning next.
Nick Paton Walsh reports.
Chairman of the House Intelligence Committee, Republican Congressman Mike Rogers is OutFront with his take on al-Baghdadi
Senior U.S. officials and diplomats tell CNN President Obama has asked for a review of U.S. policy toward Syria, admitting his initial ISIS strategy was a miscalculation.
The sources say the President has realized the defeat of ISIS cannot happen without the toppling of Syrian President Bashir al Assad.
Why this admission now?
OutFront, Senator Saxby Chambliss is the top Republican on the Intelligence Committee.