...The result of these intellectual disputes was a schism in the ranks of the foreign-policy elite that persists today. On one side are what might be called the gloomy realists. These are the heirs to Mr. Kissinger who retain a faith in multilateral cooperation, international organizations and the primacy of diplomacy and who worry over whether America has the will and resources for an ambitious foreign policy. On the other side are the Vulcans, who focus on U.S. military strength and urge its use to deter or roll back threats to national security. The arguments of the Vulcans clearly informed Ronald Reagan's administration--with its emphasis on a military buildup and its confidence in America's purpose in the world. That same confidence--and the willingness to use force--have obviously been critical to George W. Bush's response to 9/11.

Of course, the Vulcans do not agree on everything. The Powell-Armitage State Department, Mr. Mann notes, often finds itself at odds with the Rumsfeld-Wolfowitz Pentagon. But he is careful not to overplay this theme. As Mr. Mann makes plain, the alleged "moderates" in the debate over Iraq--Messrs. Powell and Armitage--are by any historical measure unapologetic hawks. Mr. Powell, after all, was Mr. Reagan's national security adviser and a fervent advocate, in the 1980s, of funding the contras in Nicaragua. Mr. Armitage was one of the last Americans to leave Vietnam, a true believer who never doubted that the cause of that war was just.

Mr. Wolfowitz, for his part, emerges from Mr. Mann's narrative as the deepest and most iconoclastic thinker of them all. His critics depict him as a trigger-happy neoconservative, desperate for any excuse to depose Saddam Hussein. Mr. Mann puts the lie to such vaporings. Although he takes issue with some of Mr. Wolfowitz's reasoning, Mr. Mann clearly recognizes that, for decades, the deputy defense secretary has made the case for an aggressive foreign policy built on the optimistic view that America will use its military strength as a force for good. Although Mr. Wolfowitz issued warnings about Iraq as far back as the late 1970s, Mr. Mann argues that they should not be read as signs of ideological obsession. Mr. Wolfowitz's idealism, he notes, is "usually followed along behind hard-nosed judgments about American interests."[...]