American strategic analyst Katherine Zimmerman says in a report entitled “The Al Qaeda Network: A New Framework for Defining the Enemy”:

“Al Qaeda has been the most lethal and effective enemy of the United States since the end of the Vietnam War and shows every indication of continuing its determined efforts to kill Americans.

The Al Qaeda network is adaptive, complex, and resilient. Today, it has a formal organizational structure, with the core group at its head providing overall direction. Even as the network becomes increasingly decentralized, the core group continues to direct the al Qaeda network. The decentralization of the al Qaeda network has not made it weaker. On the contrary, affiliate-to-affiliate relationships may have increased the overall network’s resiliency. These relationships may also ensure al Qaeda’s survival even if the core group is defeated completely.

Al Qaeda affiliates have evolved and now threaten the United States as much as (if not more than) the core group; they can no longer be dismissed as mere local al Qaeda franchises”