Al-Qaeda and allied groups continue to pose a threat to the United States. Although it is less severe than the catastrophic proportions of a 9/11-like attack, the threat today is more complex and more diverse than at any time over the past nine years. Al-Qaeda or its allies continue to have the capacity to kill dozens, or even hundreds, of Americans in a single attack. A key shift in the past couple of years is the increasingly prominent role in planning and operations that U.S. citizens and residents have played in the leadership of al-Qaeda and aligned groups, and the higher numbers of Americans attaching themselves to these groups. Another development is the increasing diversification of the types of U.S.-based jihadist militants, and the groups with which those militants have affiliated. Indeed, these jihadists do not fit any particular ethnic, economic, educational, or social profile.