"The most important points of comparison are the respective aftermaths of the two world wars. Following the first, the United States spurned Wilson’s architecture of peace and turned instead to realism. Realists may claim that the ensuing twenty years, the most catastrophic era of American foreign policy, ought to be charged up to “isolationism” rather than laid at their doorstep. But this would be a semantic dodge. Isolationism is nothing more than realism in an extreme variant... And it led directly to the most disastrous event in human history, a war that snuffed out some 60 million lives, including more Americans than have died in all of our other foreign wars combined.
"After the Second World War, in contrast, America turned to what we would today recognize as a 'neocon' approach. By this I mean that we set out on the most globalist path that any noncolonialist power has ever undertaken. We formed alliances in Europe, Northeast and Southeast Asia, the Middle East and the antipodes; girdled the globe with military bases; fostered international institutions that helped restore the world economy and gave away an impressive fraction of our income in foreign aid. Above all, we proclaimed a strategy that defined the entire world as the arena in which we would confront our new adversary. This insistence that our own security was linked to the security of others in every corner of the world was the very antithesis of “realism.” Senator Robert Taft bemoaned that we were acting as “demigod and Santa Claus to solve the problems of the world.”
"... While realist policy following the First World War led to unparalleled disaster, neocon policies after the second achieved what was arguably the most perfect success in the history of statecraft—our relatively bloodless victory over a foe possessing the most ponderous military machine ever assembled."
"[R]ealists keep a keen eye on the balance of power and oppose squandering blood or treasure on needless military buildups or ideological crusades. They know military force is the ultimate guarantor of security, but they recognize that it is also a blunt instrument whose effects are unpredictable. Realists are therefore skeptical of grandiose plans for global social engineering and believe that force should be used only when vital interests are at stake.
"Realists appreciate the power of nationalism and understand that other states usually resist outside interference and defend their own interests vigorously. Thus, realists discount the possibility that adversaries will form a tightly unified monolith and favor undermining opponents through “divide and conquer” strategies. Realists also recognize that successful diplomacy requires give-and-take and that the pursuit of U.S. interests sometimes requires cooperating with regimes whose values we find objectionable. In short, realists know that successful statecraft requires strength, cold-eyed calculation, flexibility and a keen sense of the limits of power.
"Yet realists are neither moral relativists nor disinterested in values. Realists are aware that all great powers tend to think that spreading their own values will be good for others, and that this sort of hubris can lead even well-intentioned democracies into morally dubious ventures. Realists do cherish America’s democratic traditions and commitment to individual liberty, but they believe these principles are best exported by the force of America’s example and not by military adventures. They also know that prolonged overseas meddling is likely to trigger a hostile backlash abroad and force us to compromise freedoms at home."