Tuesday’s terrorist attack in New York City, committed by an immigrant from Uzbekistan, is a reminder that radical political Islam won’t end with the recent defeat of Islamic State in Raqqa.

Just as the fall of the Taliban in Afghanistan soon after 9/11 did not mark the end of al Qaeda, extremist forces in the Muslim world will continue to resuscitate themselves in other forms, in other theaters. If al Qaeda was Jihad 1.0 in our era, and ISIS was Jihad 2.0, we should now prepare for Jihad 3.0. Islamism will continue to be...