As the 10th anniversary of 9/11 approaches, something unexpected has happened: the ideology that 9/11 made famous—neoconservatism—has died. The evidence is all around us. In Pakistan, the Obama administration has just executed Al Qaeda’s second in command, Atiyah Abd al-Rahman, dealing another blow to a network whose defeat, according to Defense Secretary Leon Panetta, is now “within reach.” Post-9/11, neoconservatism posited that jihadist terrorism was the greatest foreign-policy threat of our age, a threat on par with Nazi Germany and the Soviet Union. And it insisted that the only way to defeat that threat was to remake the Middle East through military force.

Today, by contrast, it is increasingly obvious that the real successor to German fascism and Soviet communism is not Al Qaeda, whose mud-hut totalitarianism repels the vast majority of Muslims. It is China’s authoritarian capitalism, the first nondemocratic ideology since the 1930s to challenge the idea that democracy is the political system best able to promote shared prosperity. And not only is Al Qaeda sliding into irrelevance, its demise is being hastened by exactly the narrowly targeted policies that neoconservatives derided.

The Obama administration is destroying Al Qaeda not by remaking Afghanistan—a project that looks increasingly far-fetched—but through intelligence cooperation and drone strikes. And while political change—and maybe even democracy—is indeed coming to the Middle East, it is coming because younger Muslims are fed up with corruption and dictatorship, not because of anything done by the Fourth Infantry Division. At around the time of the Iraq War, Francis Fukuyama—who famously argued that “history was over” because democracy was the only viable ideology left standing—compared himself to the neoconservatives with whom he had broken ranks. Fukuyama explained that he was a “Marxist”: he believed that democracy would spread organically because it fit people’s deepest yearnings. The neocons, by contrast, were “Leninists:” they believed that the American military needed to give history a push. Today the matter is settled. The neocons were wrong and Fukuyama was right.

But to grasp neoconservatism’s demise, you don’t need to look at the Middle East. Just look at the Republican presidential race. None of the major candidates is attacking President Obama along neoconservative lines. None is focusing on his withdrawal from Iraq or his timetable for exiting Afghanistan or his refusal to bomb Iran. The one Republican candidate with a truly coherent foreign policy vision—Ron Paul—is attacking Obama for acting too much like a neoconservative. The other candidates don’t have any coherent critique at all, because while they know they’re supposed to call Obama an appeaser, they also know that even Republican voters have little appetite for the neoconservative agenda of continued war in the Middle East.

Post-9/11 neoconservatism relied on a near-infinite supply of public will. To paraphrase Walter Russell Mead, neoconservatives may have grabbed the wheel of American foreign policy after 9/11, but they were able to drive it only so far because 9/11 had supercharged the engine. The engine was the American public’s willingness to expend blood and treasure across the globe. Today the engine is sputtering. Most Americans no longer believe that what we’re fighting for in Afghanistan is worth the cost of young American lives (even if the lack of a draft keeps them from taking to the streets to say so). And most Americans believe, rightly, that we can’t afford the war either. In retrospect, perhaps the most remarkable feature of post-9/11 neoconservative foreign policy was its virtual disregard for economics. None of the major neoconservative writers—Robert Kagan, Charles Krauthammer, William Kristol, Bernard Lewis—dealt much with international economic questions. And none of the key Bush administration hawks—Dick Cheney, Donald Rumsfeld, Paul Wolfowitz, John Bolton, Richard Perle—focused on economics either. Undergirding post-9/11 neoconservatism was the assumption that the money for a quasi-imperial foreign policy would always be there, and that, if necessary, domestic spending could always be slashed—and perhaps even taxes raised—to make sure the Pentagon was spared the ax. But that assumption no longer holds. Forced to choose between health-care spending and military spending, as they increasingly must do, most Democrats will choose the former. And forced to choose between military spending and tax hikes, Republicans in this Tea Party era will throw the Pentagon under the bus as well.

Post-9/11 neoconservatism was a doctrine that rejected limits. Now that limits are becoming, painfully, the centerpiece of American political debate, it’s no longer a plausible vision of America’s relationship to the world. While no one can be sure what will replace it, it’s at least possible that some on the right will come to remember that there was a time when neoconservatism meant something radically different than it does today. In 1997, Irving Kristol, the “godfather” of an earlier species of neoconservatism, one with a deep appreciation for the limits of government wisdom and power, predicted that “one of these days, the American people are going to awaken to the fact that they have become an imperial nation, even though public opinion and all of their political traditions are hostile to the idea.” Today, it seems, they are awakening. And as they do, neoconservatism’s best hope for survival is to relearn what an earlier generation of neoconservatives understood: that since America’s resources will always be finite, its ambitions must be too.