PIROTA, Bosnia-Herzegovina -- Finka and Ivo Bosnjak got a rude surprise when they returned home last month to this mostly Moslem region after more than a year of roaming from village to village as refugees in Croatia. The top floor of their three-story house was occupied by Moslem newlyweds, the bottom by a Moslem family of six.


The couple upstairs, refugees from Serb "ethnic cleansing" in Banja Luka to the north, had appropriated their refrigerator. The family below, tossed out of their homes by Croat gunmen in Vitez to the east, had pinched their pots and pans. All the kids in the neighborhood were picking their unripened grapes and plums, driving Finka to distraction.


The Bosnjaks, an elderly Catholic couple, had nowhere else to go, so they moved back into their house, occupying the middle floor. Last week the local Moslem government, in violation of a peace agreement with the Croats, gave the Bosnjaks until Sunday to get out of town. But the Bosnjaks refuse to go.


"They'll have to cut our throats," said Finka. "Maybe that's what they want."


The daily soap opera that unfolds in house No. 80 in this hillside village just south of the central Bosnian city of Travnik is a microcosm of the troubles faced by thousands of people in this region following successful negotiations, brokered by the United States, to end the year-long war between Bosnia's Croats and Moslems.


The Bosnjaks' once-trim white house by a gurgling brook provides a metaphor for Bosnia. Unable to find enough space to live separately, the peoples of this mountainous land are doomed to live as one.


The arguments around the Bosnjaks' table -- over cutlery, a pastry roller, grapes, loud children and blaring rock and roll -- also provide a potent illustration of the difficulties an even-more-intractable peace plan will face should it be implemented. That is the one between the Moslems and the Serbs. The plan, negotiated by the United States, Russia and major West European powers, was presented to the Moslem and Serb factions earlier this week. On Wednesday they are supposed to present their response.


One of the lessons the Croat-Moslem accord has taught United Nations officials is that even with a deal, nothing is assured. In order for any peace plan to be carried out fully, UN officials in this region say, all the parties must be placed under continual pressure.


The problem, however, is that in central Bosnia, this is not happening.


Four months after the United States worked out its first and indeed only major diplomatic success in Bosnia's 27-month-old war, Moslems and Croats have essentially been left alone to pick up the pieces of their shattered lives and to reestablish some semblance of trust following one of the most brutal chapters in Europe's bloodiest conflict since World War II.


The lightly manned UN force here has essentially been given the task of implementing the U.S. plan. But it has neither the manpower nor the expertise to do so.


While the United States promised to help Moslems and Croats bring peace to the region, little has been done so far, according to U.S. diplomats. For example, a plan to bring in teams from the U.S. Agency for International Development has yet to be realized because of concerns about safety.


A U.S. diplomat in the region said Washington is apparently unaware of the problems in the Croat-Moslem accord.


"No one seems to realize that we need to be more involved," the diplomat said. "Unless we engage more on the ground, this thing could collapse."


Beginning this week, authorities in the predominantly Moslem town of Travnik began enforcing an astonishing new rule: The town's public kitchen, which kept thousands of needy people alive during the toughest times last winter, is no longer serving Croats.


Mustafa Indzic, the president of the local Moslem charity, Merhamet, justified his decision with the fact that Croat forces to the south of Travnik will not let him leave the city to buy food in Croatia and bring it home.


"Why should we help their people if they won't let me help mine?" he said.


Indzic's logic is as indisputable as it is destructive. Croat forces do indeed block Moslems from traveling freely in their territory despite a peace accord that guarantees freedom of movement.


When they do allow Moslems to move they charge an extra $30 a head for "processing." This sum represents a huge fee in a country where the average salary hovers around $2 a month.


But at Travnik's Catholic church, the Reverend Pavo Nikolic also appears to have right on his side, arguing that Indzic is wrong to take out his anger on the weakest members of the Croat community. As such, he is refusing to channel any more aid from the Catholic charity Caritas to the kitchen.


In an indication of just how badly the area needs negotiators, both men requested a reporter to act as an interlocutor to work out the problem.