October 23, 2007 | Op-Ed Contributor | By PETER W. GALBRAITH Townshend, Vt.

IN a surge of realism, the Senate has voted 75-23 to acknowledge that Iraq has broken up and cannot be put back together. The measure, co-sponsored by Joe Biden, a Democratic presidential candidate, and Sam Brownback, Republican of Kansas, supports a plan for Iraq to become a loose confederation of three regions — a Kurdish area in the north, a Shiite region in the south and a Sunni enclave in the center — with the national government in Baghdad having few powers other than to manage the equitable distribution of oil revenues.

While the nonbinding measure provoked strong reactions in Iraq and from the Bush administration, it actually called for exactly what Iraq’s Constitution already provides — and what is irrevocably becoming the reality on the ground.

The Kurdish-dominated provinces in the north are recognized in the Constitution as an existing federal region, while other parts of Iraq can also opt to form their own regions. Iraq’s regions are allowed their own Parliament and president, and may establish their own army. (Kurdistan’s army, the peshmerga, is nearly as large as the national army and far more capable.) While the central government has exclusive control over the national army and foreign affairs, regional law is superior to national law on almost everything else. The central government cannot even impose a tax.

Iraq’s minimalist Constitution is a reflection of a country without a common identity. The Shiites believe their majority entitles them to rule, and a vast majority of them support religious parties that would define Iraq as a Shiite state. Iraq’s Sunni Arabs cannot accept their country being defined by a rival branch of Islam and ruled by parties they see as aligned with Iran. And the Kurdish vision of Iraq is of a country that does not include them.

The absence of a shared identity is a main reason the Bush administration has failed to construct workable national institutions in Iraq. American training can make Iraq’s Shiite-dominated security forces more effective, but it cannot make them into neutral guarantors of safety that the Sunnis can trust. The Kurds ban the national army and police from their territory.

In a reflection of Iraq’s deep divisions, the country’s Shiite prime minister, Nuri Kamal al-Maliki, and the main Sunni parties denounced the Senate vote as a plot to partition Iraq, while Kurdish leaders, along with a leading Shiite party, embraced the resolution precisely because they hope it will lead to the partition.

Senator Biden, probably the best-informed member of Congress on Iraq, insists that loose federalism, not partition, is his goal. He makes an analogy to Bosnia, where the 1995 Dayton agreement has kept that country together by devolving most functions to ethnically defined entities. He has a point: Iraq’s Kurdish leaders are willing to remain part of Iraq for the time being because Kurdistan already has all attributes of a state except international recognition.

But over the long term, the former Yugoslavia and the Soviet Union are better analogies to Iraq than Bosnia. Democracy destroyed those states because, as in Iraq, there was never a shared national identity, and a substantial part of the population did not want to be part of the country.

So we should stop arguing over whether we want “partition” or “federalism” and start thinking about how we can mitigate the consequences of Iraq’s unavoidable breakup. Referendums will need to be held, as required by Iraq’s Constitution, to determine the final borders of the three regions. There has to be a deal on sharing oil money that satisfies Shiites and Kurds but also guarantees the Sunnis a revenue stream, at least until the untapped oil resources of Sunni areas are developed. And of course a formula must be found to share or divide Baghdad.

At the regional level, Iraq’s neighbors have to be reconciled to the new political geography. The good news is that partition will have the practical effect of limiting Iran’s influence to southern Iraq and parts of Baghdad.

Turkey, understandably angry over terrorist attacks by a Turkish Kurdish rebel group, the Kurdistan Workers Party, has in recent days threatened to strike at the group’s sanctuaries on the Iraqi side of the mountainous border. In general, however, Turkey has adopted a pragmatic attitude toward the emergence of a de facto independent Kurdistan, in part by supporting the Turkish companies that now provide 80 percent of the foreign investment in Iraqi Kurdistan.

Those who still favor a centralized state like to insist that partition would further destabilize the country. But current events suggest otherwise. Iraq’s most stable and democratic region is Kurdistan. In Sunni-dominated Anbar Province, the Americans abandoned a military strategy that entailed working with the Shiite-dominated Iraqi Army and instead moved to set up a Sunni militia. The result has been gains against Al Qaeda and a substantial improvement in local security.

Let’s face it: partition is a better outcome than a Sunni-Shiite civil war. There is, in any event, little alternative to partition. Iraq cannot be reconstructed as a unitary state, and the sooner we face up to this reality, the better.

Peter W. Galbraith, a former United States ambassador to Croatia and the author of “The End of Iraq,” is a principal in a company that does consulting in Iraq and elsewhere.