Faced with evil, Americans always want to be on the side of the angels. So American interventionists, hawks, and human-rights types are banding together, as they did in Libya, to stop President Bashar al-Assad from killing his people. But when interventionists become avenging angels, they blind themselves and the nation, and run dangerously amok. They plunge in with no plans, with half-baked plans, with demands to supply arms to rebels they know nothing about, with ideas for no-fly zones and bombing. Their good intentions could pave the road to hell for Syrians—preserving lives today, but sacrificing many more later.