"In a series of studies culminating in their new book, "Electing to Fight," the political scientists Edward D. Mansfield and Jack Snyder argue that new democracies are often unstable and thus particularly warlike...Elihu Root, who'd been Theodore Roosevelt's secretary of state, said in 1917: "To be safe, democracy must kill its enemy when it can and where it can. The world. . . must be all democratic or all Prussian.""