"It is also far from clear that killing leaders is even a reliable means of disrupting terrorist groups like Al Qaeda. Jenna Jordan, of the Georgia Institute of Technology, and Aaron Mannes, of the University of Maryland, have separately reviewed dozens of past campaigns by governments to destroy terrorist organizations and found that culling leaders works in some instances—especially when terrorist groups are young and small—but not in others. The approach is particularly ineffective against religious organizations, which tend to regroup and escalate violence in response to such efforts."