With cars being used as weapons to kill and maim the innocent as seen in Germany, Paris & know London how does society defend itself? We are not going to be able to ban cars or crowds so that is off the books? Better surveillance of those who might become radicalized will help, as well as making sure we fight the war over there instead of on our streets but other defensive mechanism must be adopted. There needs to be more street barriers where crowds normally gather including tourist locations. These barriers would disable vehicles before an attack could occur. We also must have more drones in the air that can monitor such street traffic constantly and offensively hit a target if it attempts to weave into public squares. The truth is in this war against pure evil we have to use our greatest minds to find creative ways to stop the threats we face in our normal average day life before such acts stop us from truly living in free open societies.