IN the Bosnian city of Mostar, a beautiful Ottoman-era limestone bridge called the Stari Most arched over the Neretva River for 427 years, surviving earthquakes and two world wars. After a barrage of shelling in 1993, during the Bosnian civil war, the bridge collapsed. Citizens were stranded on opposite sides of the riverbank. Ethnic strain wasn't the cause. It was the effect. Across the country, the war itself was dividing citizens into three ethno-nationalist clusters: Bosnian Serbs, Bosnian Croats and Bosnian Muslims (Bosniaks). Twenty years after the war began, and 17 years after the Dayton accords brought the fighting to an end, the bridge stands again, and a shallow peace prevails. But now, the compromises we made to end the killing increasingly look inadequate, and it's time to begin fixing them. [ABSTRACT FROM AUTHOR]