Terrorism has come to look very different from what confronted the West over a decade ago.

Most ad hoc commissions come and go without a trace. Not so, the 9/11 Commission. Its final report became a national bestseller. Its findings served as the touchstone for explaining what happened on that dreadful day the terrorists went after New York City and Washington, D.C. Even more important, the report framed the argument of where the nation should go from here.