Almost two years after the Americans withdrew from Iraq, the autonomous Kurdish region in the north looks to be their only real success story. Whereas Shia and Sunni Arabs in the rest of the country battle for control of the central government, the Kurds are quietly prospering. Yet the United States will hardly support their efforts.

Protected by a no-fly zone during the period between Saddam Hussein’s defeat in the 1991 Gulf War and the 2003 invasion, Iraq’s Kurds were able to build the institutions they needed for an independent state: a parliament, government departments of their own and separate intelligence and military services. The sectarian conflagration that characterized the last war and increased once again after the Americans pulled out in late 2011 has largely spared Kurdistan.

The region is also increasingly independent economically. It has attracted foreign investments, especially from Turkey, and is now able to export oil into that country over land — over the objections of Prime Minister Nouri al-Maliki’s government in Baghdad which insists it alone has the right to export petroleum.

Maliki, a Shia Muslim, likely fears that if the Kurds move further toward secession, Iraq’s Sunnis, who have been largely sidelined from his administration, might consider following their lead. That could fracture Iraq and leave a rump government in Baghdad virtually without oil revenue which provides up to 90 percent of its income.

Another dispute between Baghdad and the Kurds involves the historic city of Kirkuk which is surrounded by oilfields. Its Kurdish and Turkmen residents are resistant to Arab rule but a referendum to decide its fate has been repeatedly delayed. The Kurds could do without Kirkuk economically but many feel an emotional attachment to the city.

Kurdish independence is not without its internal challenges either. The region’s politics are deeply polarized between President Masoud Barzani’s Kurdish Democratic Party, which is dominant in the capital Irbil and Dohuk in the north, and the leftist Patriotic Union of Kurdistan, which largely controls Sulaymaniyah, Kurdistan’s largest city. The two share power in a coalition government but remain mistrustful of one another.

However, the disconnect between the two parties pales in comparison to the disconnect between the Kurds and Iraq’s Arabs. Very few Kurds under the age of thirty speak Arabic, English being the favored second language, “and not a single person I met of any age believed themselves to be Iraqi,” reported the Council on Foreign Relations’ Steven A. Cook after visiting the region. “Why would they?” he wondered. “What is the common idea that ties someone from Sulaymaniyah to someone in Basra? There isn’t one.”

Nevertheless, it is the United States’ policy to advocate the integrity of the Iraqi state, even when that integrity doesn’t exist and the illusion of one created a dangerous standoff as recently as December of last year when central government and Kurdish paramilitary forces clashed in the Kirkuk area.

Neither Maliki’s government nor the Kurds want a military confrontation and the latter claim they have no designs for secession. But Cook predicted that a “Kurdish state will just come into being. It is already happening.” America’s ambivalence is merely a complication. Without troops left in the country and Maliki susceptible to Iranian rather than American influence, there is little the United States can do to stave off the disintegration of a country for which several thousands of its servicemen and -women died.