What to do about ISIS? Following President Obama’s announcement of an expanded campaign against the Islamic State that will pair targeted air strikes with local capacity building for Kurds and Iraqi troops, a range of responses. Jim Lindsay argues that the campaign’s success will hinge on domestic American support. Peter Beinart believes that the threat to the homeland has been overstated. And Tom Ricks sees this as a continuation of a war that has raged uninterrupted since 1990.