Terror threat

ISIS seen building capacity for mass casualty attacks

Some in the U.S. intelligence community warn that ISIS may be working to build the capability to carry out mass casualty attacks, a significant departure from the terror group's current focus on encouraging lone wolf attacks, a senior U.S. intelligence official told CNN on Friday.

To date, the intelligence view has been that ISIS is focused on less ambitious attacks, involving one or a small group of attackers armed with simple weapons. In contrast, al Qaeda in the Arabian Peninsula, or AQAP, has been viewed as both more focused on -- and more capable of -- mass casualty attacks, such as plots on commercial aviation. Now the intelligence community is divided.