America is a nation disillusioned by its recent wars and largely averse to becoming embroiled again in foreign conflicts. But Eliot Cohen makes a strong, historically grounded and clearly reasoned case in The Big Stick for America not to pull back from its leadership role in the world and to be ready and willing to use force if necessary. Cohen, who is a professor of strategic studies at Johns Hopkins School of Advanced International Studies, urges preparedness, not belligerence, as Philip Zelikow says in a blurb for the book. Given today’s major multiple threats—China, North Korea, Iran, Russia, the Islamic State, cyberwarfare, space-based weapons—and given the reluctance or inability of other powers on our side to act, Cohen argues that a failure to exercise military power could prove calamitous. He notes that today’s array of challenges has no exact comparison with the past, so new approaches will need to be devised, and he puts forward his own set of general guidelines for when to use force.