Al-Qaeda-affiliated groups are not flourishing in hotbeds of Islamic radicalism like Saudi Arabia. They thrive instead in Yemen, Somalia, Mali and northern Nigeria. Some of these groups have real ties to al-Qaeda and share its goals. Others, like the ones in Africa, look like local warlords using the label to burnish their brand.
At the moment, only the U.S. has the technology, missiles and troops to disrupt terrorist plots being hatched in those countries. Yet the best policy in the long run would be to shift the struggle over to locals, who can most effectively win a long war against militants in territory they know better than any outsiders.
For another take see Ted Koppel, writing in The Wall Street Journal:
Will terrorists kill innocent civilians in the years to come? Of course. They did so more than 100 years ago, when they were called anarchists—and a responsible nation-state must take reasonable measures to protect its citizens. But there is no way to completely eliminate terrorism.
The challenge that confronts us is how we will live with that threat. We have created an economy of fear, an industry of fear, a national psychology of fear. Al Qaeda could never have achieved that on its own. We have inflicted it on ourselves.