Back in 2010, al Qaeda called for terrorist recruits to use trucks to “mow down the enemies of Allah.” In 2014, the Islamic State (ISIS) told fighters if they couldn’t find an IED or a bullet they should kill unbelievers with a knife, rock, or poison, or “run over him with your car.” True to form, in Nice, Berlin, Barcelona, Stockholm, and London, Islamic terrorists used vehicles to mount deadly attacks. Uzbek Muslim Sayfullo Saipov, acting on behalf of the Islamic State, used a rented truck to murder eight victims in New York City last October. Monday’s attack in Toronto...