Although President Obama insists that America's goal in Afghanistan is to disrupt, degrade, and defeat al-Qaeda, it is apparent that the objective is much broader than that. U.S. and NATO officials speak of supporting an indigenous political structure that will provide security to the Afghan people and implement good governance. Since the U.S.-led invasion that overthrew the Taliban government in late 2001, hordes of Western military and civilian personnel have been involved in everything from setting up schools to drilling wells to building roads. Although they avoid using the term nation-building, that is clearly what is taking place.

Not only is Afghanistan an extremely unpromising candidate for such a mission, given its pervasive poverty, its fractured clan-based and tribal-based social structure, and its weak national identity, U.S. and NATO officials should also be sobered by the disappointing outcomes of other nation-building ventures over the past two decades. An audit of the two most prominent missions, Bosnia and Iraq, ought to inoculate Americans against pursuing the same fool's errand in Afghanistan.

The Dayton Accords ended the Bosnian civil war nearly fourteen years ago. Yet as Washington Post correspondent Craig Whitlock discovered during a recent visit, Bosnia is no closer to being a viable country than it was in 1995. It still lacks a meaningful sense of nationhood or even the basic political cohesion and ethnic reconciliation to be an effective state. The reality is that if secession were allowed, the overwhelming majority of Bosnian Serbs would vote to detach their self-governing region (the Republika Srpska) from Bosnia and form an independent country or merge with Serbia. Most of the remaining Croats-who are already deserting the country in droves--would also likely choose to secede and join with Croatia. Bosnian Muslims constitute the only faction wishing to maintain Bosnia in its current incarnation.

Political paralysis continues to plague the country. To the extent that political power has been exercised by Bosnia's inhabitants at all, it has been at the subnational level, i.e., the Republika Srpska and the Muslim-Croat federation. The national government is weak to the point of impotence. Most real political power has been exercised by the UN high representative, an international potentate who rules like a colonial governor. High representatives have routinely removed elected officials from office, disqualified candidates for elections, and imposed various policies by decree.

The economic situation is not much better. Bosnia's economy is in terrible shape. Indeed, without the financial inputs from international aid agencies and the spending by the swarms of international bureaucrats in the country (which account for more than a third of its gross domestic product), Bosnia would scarcely have a functioning economy at all. Even with that assistance, the country's unemployment rate stands at a staggering 45 percent.

Although Bosnia verges on being a nation-building fiasco, it eventually may be less of a disaster than Iraq. Recent events there suggest that those Americans who cheered the success of the surge strategy were premature in their elation. Violence is again on the rise, and tensions are soaring, both between Sunnis and Shiites and between Arabs and Kurds.

Iraq has already ceased to be a unified state. The Baghdad government exercises no meaningful power in the Kurdish region in the north. Indeed, Iraqi Arabs who enter the territory are treated as foreigners-and not especially welcome foreigners. Although the Kurds have not proclaimed an independent country, in every sense that matters Iraq's Kurdistan region is de-facto independent, and the "Kurdish regional government" is the governing body of a sovereign state with its own flag, currency, and army. Moreover, it is a de facto sovereign state with far-reaching territorial ambitions. The Kurds claim the city of Kirkuk and its extensive oil deposits. There have also been nasty clashes with Iraqi Arab factions in the ethnically mixed province of Ninevah, where Kurds insist that several villages should be under the jurisdiction of the Kurdish region.

Kurdish-Arab tensions have grown so severe that Secretary of Defense Robert Gates made an unexpected trip to Iraq in late July to urge both sides to back away from a dangerous confrontation. General Ray Odierno, the top U.S. commander in Iraq, admits that the Arab-Kurdish feud-especially over the status of Kirkuk-is the "number one driver of instabilities" in the country. Tensions in both the area around Kirkuk and in Nineveh province are so palpable that Odierno has suggested that U.S. troops be deployed to establish a buffer between Kurds and Arabs to prevent an outbreak of open warfare.

There are also serious questions about the degree of stability in the rest of Iraq. True, the carnage that afflicted the country following the U.S. invasion, and which reached especially severe levels from early 2006 to mid 2007, has declined. Nevertheless, the casualty rates are still disturbingly high. Shiite-Sunni sectarian tensions simmer, and the massive bombings in Baghdad and other cities in mid-August suggest that they may soon again come to a boil.

Even the improvement in the casualty numbers should not be overstated. According to the Ministry of the Interior, there were 437 deaths in July. Since Iraq's population is only 25 million, the July toll would translate into an equivalent of more than 5,000 deaths from political violence in the United States-or an annual rate of more than 60,000. Iraq is still in the throes of a civil war, albeit a relatively low-intensity one. That does not bode well for unity or even stability going forward. There are already calls by American pundits to abandon-or at least delay-plans for the withdrawal of all U.S. combat forces by the end of 2011, lest Iraq again erupt into chaos.

Despite a fourteen-year effort and the expenditure of billions of dollars, the Bosnian nation-building mission is a failure. Despite a six-year effort (and counting), the expenditure of at least $700 billion, and the sacrifice of more than 4,300 American lives, the Iraq nation-building mission is failing. Yet, instead of learning from those bitter experiences, U.S. leaders seem intent on pursuing the same chimera in Afghanistan.

As Council on Foreign Relations president Richard Haass has suggested, we need to "define success down" in Afghanistan. That means abandoning any notion of making ethnically fractured, pre-industrial Afghanistan into a modern, cohesive nation state. It means even abandoning the goal of a definitive victory over al-Qaeda. Instead, we need to treat the terrorist threat that al-Qaeda poses as a chronic, but manageable, security problem. That requires a willingness to work with any Afghan faction prepared to oppose the organization, harass it, and keep it off balance. Such a modest approach would be an imperfect and unsatisfying strategy, but foreign policy, like domestic politics, is the art of the possible. Containing and weakening al Qaeda may be possible, but building Afghanistan into a modern, democratic country is not. The increasingly evident failures of nation-building in Bosnia and Iraq-which were both more promising candidates than Afghanistan-should have taught us that lesson.

Ted Galen Carpenter, vice president for defense and foreign-policy studies at the Cato Institute, is the author of eight books, including Smart Power: Toward a Prudent Foreign Policy for America (2008), and the co-author with Malou Innocent of a forthcoming Cato policy analysis, Escaping the "Graveyard of Empires": A Strategy to Exit Afghanistan (September 2009). He is also a contributing editor to The National Interest.