BEFORE THE war in Iraq, Bush administration policymakers used to deride the elaborate nation-building regime the Clinton administration and the European allies created in Bosnia. Now, perhaps, they might learn something from it. Ten years after the United States brokered the end of a bloody civil war that killed more than 200,000 people, Bosnia remains at peace and is inching toward reconciliation, thanks to the continued presence of Western peacekeeping troops, an international overseer and aggressive multilateral diplomacy. Its leaders agreed last week to prepare constitutional reforms by next March that will knit the country closer together and make effective policing and foreign investment more feasible. They also opened negotiations with the European Union on an association agreement. Though it will probably take another decade, the bloodiest battleground of the Balkan wars of the 1990s at last appears headed toward becoming a stable part of Europe.

To its credit, the administration has helped Bosnia along in recent months after conspicuously ignoring the Balkans during President Bush's first term. Undersecretary of State Nicholas Burns pushed for the constitutional agreement, which was announced in Washington; he also persuaded Bosnian Serb leaders to publicly call for the surrender of indicted war criminals Radovan Karadzic and Ratko Mladic. The reforms are meant to remedy the weaknesses of the 1995 Dayton accords, which created a loose confederation in Bosnia featuring two self-governing republics and three presidents. Though it succeeded in ending the war, the peace deal left Bosnia to limp along under a powerful international high commissioner; some 7,000 of the 60,000 U.S. and European troops deployed a decade ago are still there. If the new reforms take hold, the high commissioner will relinquish power. But foreign troops will probably remain for some time, and Bosnia will remain under the tutelage of the European Union for years while preparing for membership.

Some of the architects of the Iraq invasion regarded Bosnia as an example of how excessive international interference could breed dependence and prevent postwar reconstruction. But the real lesson it offers is how active and sustained international intervention must be to rescue a failed state. Communities that have been slaughtering one another -- like the Bosnian Muslims, Serbs and Croats -- cannot create and accept a new political system overnight. Establishing security and rebuilding a minimal level of trust is the work of many years. After a decade of Western peacekeeping, political supervision and development aid, Bosnia at last seems to be moving forward, but its own leaders say it may be another decade before they live in a normal country. As Americans think about how to stabilize Iraq and Afghanistan, Bosnia offers a sobering measure of what may be required.