Back when al-Qaeda was the focus of attention, you heard plenty about people, including Americans and other Westerners, being radicalized by them and&#x2F;or via a system of radical madrassas (mostly in Pakistan) and radical networks (throughout the world) associated with them and their ideology.<p>It&#x27;s true that the mechanisms were different, because social media wasn&#x27;t a big thing at the time: John Walker Lindh was radicalized before the services that really made &quot;social media&quot; a global force existed.