Karic and his family fled Kijevo in 1992 for a Serb-owned home in Tarcin, a mostly Muslim town west of Sarajevo. During the war, the Muslim-dominated Bosnian army imprisoned hundreds of Serb and Croat men inside Tarcin’s windowless grain silo, where some were allegedly tortured and killed.

Karic returned to his farm in 2000 but his parents refused to go, unwilling to live with their Serb former neighbors. He has persevered, he said, without the support of the authorities of either side.

“They won’t give me help over there because they want me out, and they won’t give me any help on this side because I don’t live here,” he said, waiting for customers in Sarajevo’s Markale market beneath a monument bearing the names of 68 people killed by a Bosnian Serb mortar shell on Feb. 5, 1994.

Fear of retaliation by Muslims and Croats has kept Strajko Trifkovic, an 80-year-old Serb, from returning to his home in Grbavica. The Sarajevo district was held by Bosnian Serb fighters who murdered and tortured Muslim and Croat residents.

Trifkovic, living on a monthly pension of about $200, prefers to stay with some 30 other poor, displaced Serbs. They share a dilapidated building on the former Bosnian Serb army base in Lukavica, outside Sarajevo in the Serb republic.

“I came here when the first shots (of the war) were fired. After the war, I partly repaired my home, but it was broken into and I decided not to return. Even if it was fully repaired, I won’t return,” said Trifkovic, whose youngest daughter died in a May 1995 NATO airstrike on Lukavica.

Trifkovic is among some 8,600 Bosnians displaced by the war still living in 150 “collective centers” around the country. Some 105,000 others live in properties that don’t belong to them, unwilling or unable to return to homes from which they fled or were evicted.

“There were people who were fighting on the other side now living in the homes around mine, so I wouldn’t be safe there,” said Trifkovic, casting a rheumy-eyed glance toward the city. “This is supposed to be one country, but I don’t think it ever will be again. When you split an apple, you can’t put it back together.”

A major barrier to unity has been the nationalist parties’ refusals to reform the U.S.-brokered constitution. Doing so could end the vetoes that they use to block almost any legislation that could strengthen the central government. It took 16 months of wrangling over posts to form a government after October 2010 polls.

The worst offender, most experts and Western diplomats agree, is Republika Srpska President Milorad Dodik. He denies that Sarajevo was besieged, downplays the 1994 massacre of some 8,000 Muslim men in Srebrenica — Europe’s worst war crime since the Holocaust — and recently admitted that he is deliberately paralyzing the central government.

Reform also could end the patronage that the parties use to control public-sector jobs. In some areas, even secretaries, school janitors and “kafekuharice” — coffee makers — are appointed by ethnic and party affiliations.

There are rare instances in which members of the three ethnic groups have made common cause. The latest is in front of Parliament, where Serbian snipers fired the first shots of the siege of Sarajevo.

Dozens of men who fought each other during the war have been living for weeks under tents and plastic sheets on the sidewalk, sharing food and fiery shots of homemade brandy. They vow to remain until they’re paid the pensions they were promised when they were forcibly retired in 2010.