Washington (CNN)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.
Meanwhile, the U.S. effort to train rebels in Syria to fight ISIS is having trouble. The few rebels that the U.S. has put through training are already in disarray, with defense officials telling CNN that up to half are missing, having deserted soon after training or having been captured after last week's attack by the al-Qaeda-affiliated Nusra Front attack on a rebel site.
Advertisement - story continues below