1 At night, Emica Kevelj peers across the abyss separating east and west Mostar, at lights in the homes of her former neighbors.
2 She is a refugee in her own town, a Muslim exiled to the eastern bank of a riverside city that has become Bosnia's Berlin.
3 Mostar bore the brunt of fighting 1{ years ago between Croats and the Muslim-led Bosnian government. Now, it's a battleground of wills -- over whether a federation between Croats and Muslims, a key to peace in Bosnia, will succeed.
4 Signed last March under U.S. pressure, the Muslim-Croat federation halted the fighting between the two sides. But the hoped for military-political union never happened. Rising tensions are now pushing the federation toward collapse.
5 Croatian President Franjo Tudjman recently told the German news magazine Spiegel the Bosnian government wanted full control of Mostar as a step to 'founding an Islamic state.' Mostar's European administrator has accused Bosnian Croats of sabotaging the federation.
6 Diplomats are scrambling to save the federation, fearing its failure would further unravel attempts to stitch together a Bosnian peace plan embracing the Serbs. Assistant U.S. Secretary of State Richard Holbrooke meets Bosnian government and Bosnian Croat representatives in Germany on Sunday.
7 German Foreign Minister Klaus Kinkel visited both sides this week to urge them to make the federation work.
8 'This (federation) must work,' he said, calling it an 'element of hope and stability.'
9 The Muslim-Croat federation has reduced the number of front lines in Bosnia, improved civilian life in many central Bosnian communities and reopened land routes from Croatia. That allows the Bosnian government to arm itself despite a U.N. weapons embargo.
10 The alliance of two of Bosnia's three ethnic groups also puts pressure on Bosnian Serbs.
11 Last November, rare battlefield cooperation saw Croat and Bosnian army forces rout Serbs from Kupres, key high ground controlling access to the sea. But the Bosnian Croat militia have fought only where they have a direct interest.
12 Politically, the federation has bogged down in arguments over who gets which leadership posts.
13 The federation was supposed to operate parallel to the Bosnian government until a peace treaty was signed, and then become the governmental structure for territory held by Croats and Muslims.
14 Bosnian Croats view the federation as an alliance between two nations -- their self-proclaimed state of Herceg-Bosna and Bosnia. They insist the new power-sharing take effect now.
15 Ivan Bender, speaker of the Bosnian Croats' assembly, said the federation could work. But a condition for future cooperation -- resignation of Bosnia's Muslim president, Alija Izetbegovic -- illustrates the problems.
16 'Izetbegovic would use all means to create a fundamentalist, Islamic state in this region, and this is not in the interest of Croats or the western world,' Bender said.
17 He said the Bosnian government viewed the federation as a 'transition' to reasserting control over all Bosnia-Herzegovina. 'We will never accept that because Croats would be a minority.'
18 Bosnian Croats are in the federation only for eventual confederation with Croatia, Bender said.
19 'If we cannot solve things politically, we can always rely on the army,' Bender added. 'We will do everything in our power to avoid conflict.'
20 Once a beautiful blend of Ottoman and Austrian empire architecture, Mostar is arguably the most devastated city in Bosnia-Herzegovina. It was shelled by the Serbs in 1992 and was a front line during the Croat-Muslim fighting. Mostar, and especially its eastern side, is still largely rubble.
21 The city's symbolic heart, the 600-year-old Stari Most bridge linking east and west Mostar, was destroyed by Croat shelling in late 1993.
22 The city's Croat west bank and Muslim east bank have different currencies and police. A few people may pass between the two sides, but not men of fighting age. Mostar's west bank has electricity; its east bank is powered only for a few hours a day.
23 'The federation will stand or fall in this city,' said Mrs. Kevelj, an assistant elementary school principal who was evicted from her western Mostar home. 'I don't think any other city was hurt like Mostar.'

Signed last March under U . S . pressure , the Muslim - Croat federation halted the fighting between the two sides . But the hoped for military - political union never happened . Rising tensions are now pushing the federation toward collapse .
tensions
What are the tensions that are causing the federation to collapse?