Reuters recently reported that the United States would sail a third ship near the Chinese-built artificial islands in the South China Sea. It would be difficult for the Obama administration to telegraph more clearly it has absolutely no interest in China’s new islands. Or, for that matter, Russia’s new Ukrainian possessions, or Iran’s bludgeoning Syrian rebels into submission. To the president, these are unrelated drips and drops.

Jakub J. Grygiel and A. Wess Mitchell’s new book, The Unquiet Frontier, links them together. It is the intellectual backbone to every bumper-sticker critique about the “weakness” of Obama’s foreign policy. Their book examines America’s inaction in the face of aggressive policies by revisionist states like Russia, argues persuasively that such inaction is a disaster. Apathy towards Ukraine or Syria or the South China Sea not only cedes local stakes to the revisionist power and encourages future aggressions, but also entails a whole host of unpleasant second-order effects. Without American security, U.S. allies in the Rimlands – their preferred word for smaller states like Poland and Vietnam close to the larger revisionists – may act unpredictably, even aggressively, to stay safe.