Expectations--and Morale--Sinking in Bosnia : Balkans: Frustrated ‘blue helmets’ sit in their hotel rooms, more hostages than peacekeepers, as U.N. mission falters.

BANJA LUKA, Bosnia-Herzegovina —  In the dirt coating a U.N. jeep parked outside the Hotel Bosna here, someone has etched a Cyrillic symbol for the Serbian nationalist battle cry: “Only Unity Can Save the Serbs!”

The expansionist call to arms would be offensive to the Muslims and Croats of Bosnia-Herzegovina. But they aren’t likely to see it, because the few U.N. peacekeepers here don’t get around much.

Surrounded by Serbian vigilantes and lacking any mandate to intervene in a new conflict that has drifted their way, the hopelessly outnumbered U.N. troops in Banja Luka are keeping their blue-helmeted heads down.

“They asked us to come, and here we are,” said one disgruntled Scandinavian soldier, drinking beer in his hotel room and vainly trying to phone mission headquarters in Sarajevo. “I think there are very high expectations of what we can do here. People are going to be disappointed.”

Banja Luka and Sarajevo, both in the newly independent republic of Bosnia-Herzegovina, were chosen as administrative centers for the U.N. deployment to neighboring Croatia on the theory that a small presence here would deter any spread of the fighting. But both cities are now besieged by Serbian rebels, and the few handfuls of U.N. troops who arrived before the conflict escalated are more hostages than protectors of peace.

Ethnic unrest has so intensified that U.N. Secretary General Boutros Boutros-Ghali was forced in late April to scrap plans for a logistics center here, diverting those troops to the Serbian and Croatian capitals.

There has also been a gradual cease-fire breakdown in Croatia, where most of the 14,000 soldiers assigned to the U.N. Protection Force are to be deployed by the end of May.

Hundreds have died in fighting in the three designated deployment zones there since a truce took effect Jan. 3, and U.N. troops daily record instances of Serbs expelling other ethnic groups from the areas they control.

With clashes spreading and intensifying, those familiar with the complex Yugoslav crisis argue that the U.N. mission, already one of the largest and most costly ever undertaken, will have to be accelerated and expanded if it is to have any success.

After fighting flared in Bosnia in early April, the United Nations approved deployment of 100 observers to border areas, including this tense, Serbian-held city. But U.N. officials have been equivocal in predicting further expansion.

U.N. troops in Banja Luka refer official inquiries about their mission to headquarters in Sarajevo, which is virtually inaccessible because fighting has shut down the airport and blocked most roads and phones.

Privately, the foreign soldiers say they feel helpless to deter the violence whirling around them.

And in the meantime, Banja Luka has become a Serbian-run armed camp. At key intersections throughout the city, young men in jeans direct traffic with their Kalashnikovs.

Diplomats and international monitors describe the U.N. deployment as too slow, too uncertain and too narrowly focused to be effective.

Special U.N. envoy Cyrus R. Vance, a former U.S. secretary of state, inspired hopes for settling the Balkan conflict when he got the warring factions to agree to the deployment plan last November.

But many believe that he was successful because the plan was vague enough to let both sides think they could make it work in their favor. “Now that the U.N. is trying to cross the T’s and dot the I’s, they are encountering strong resistance,” one diplomat said.

U.S. Ambassador Warren Zimmermann said there was a debate under way, both among international mediators and the Yugoslav combatants, as to whether the areas to which the U.N. troops are being deployed should be enlarged to include other conflict sites.

Besides the new battlefields marked out over the past month in Bosnia-Herzegovina, some volatile areas of Croatia are left out of the Vance plan.

U.N. mediators have indicated that whichever force holds the areas of deployment when the peacekeepers move in will retain civilian control of that region. That has provided an incentive for both Serbian and Croatian fighters to take as much of the territory targeted for deployment as possible before the U.N. force is fully in place.

Croatian authorities have resisted expansion of the U.N.-protected areas to cities they still nominally hold for fear they would become new targets in the 11th-hour tug of war and fall under indefinite Serbian control.

The U.N. mission has also been hampered by delays, including a long pause after its February approval by the Security Council. U.N. officials then asked planners to scout ways of reducing the deployment’s estimated $634-million annual price tag.

Among the cost-saving measures proposed from New York has been a reduction in the number of civilian police troops, who are expected to disarm fighters.

Those forces also have been delayed in their arrival. Only about 8,000 of the intended 14,000 peacekeepers were in place by late April.

Postponement of the civilian contingent could undermine one of the mission’s primary aims, which is to help those who fled the fighting return to their homes.

“My feeling is that no one is going to make a move until life gets back to normal and the tension has gone down,” said Judith Kumin, a Belgrade-based representative for the Office of the U.N. High Commissioner for Refugees.

Since fighting spread to Bosnia-Herzegovina, the number of refugees in Yugoslavia has jumped from 600,000 to more than a million, the largest conflict-inspired migration since World War II.

The Vance plan’s requirement that the federal army withdraw from Croatia also appears to be doing more to relocate the conflict than resolve it.

Huge columns of federal troops, tanks and armored personnel carriers have moved from the Krajina region of Croatia to back up soldiers now fighting in Bosnia-Herzegovina.

Sarajevo authorities estimate there are 150,000 federal troops in the multiethnic republic and fear they are taking the Serbs’ side.