AS the first American ''peacekeepers'' arrive in Bosnia, contention over Serb-held suburbs of Sarajevo may threaten the US-brokered peace deal and put NATO troops at risk.
Already there are signs that optimism about the American-led NATO mission to lay down demarcation lines, and to enforce compliance with the Bosnian peace deal, may be short-lived.
The presidents of Bosnia, Croatia, and Serbia last month initialed the agreement, which effectively ends nearly four years of war.
But anger is rising among Serbs in Sarajevo suburbs who, under the agreement, will be forced to submit to Bosnian government rule. For many, the vague guarantees of security proffered by the Muslim-led government are not enough to keep them from moving - or from burning their homes as they go. President Clinton's promise that Sarajevo will once again become a ''shining symbol of multiethnic tolerance'' is an impossible dream for Sarajevo's Serbs.
Bosnian Serbs are far from willing to accept the peace as it was negotiated on their behalf last month in Dayton, Ohio, by Serbia's President Slobodan Milosevic.
Encouraged by hard-line leaders, they expect that the decision reached in Dayton may somehow be reversed at the signing ceremony in Paris on Dec. 14, so that Serb-inhabited suburbs of Sarajevo will remain under control of the newly recognized Serb entity - the Republika Srpska.
Serbs demonstrate daily in the bleak suburbs, and UN vehicles must travel through them with armed escorts. That still doesn't stop Serb snipers from taking random shots. Also, bricks, and stones are often thrown, and chairs have been used to smash windshields.
Nevertheless, the war-hardened Bosnian Serb army is capable of causing American and other NATO forces extreme difficulty in the snow and mud-covered mountains of Bosnia.
Gen. Ratko Mladic, chief of the Bosnian Serb army, who along with Bosnian Serb leader Radovan Karadzic has been indicted by the war crimes tribunal and will not be permitted to hold public office under the Dayton deal, has warned that any attempt by the Bosnian government to control Serb-held areas will be met by force.
After Serb forces laid siege to Sarajevo for 3-1/2 years - firing some 500,000 shells onto government-controlled areas in the city - few Bosnians doubt the Serb capacity to cause trouble. ''We can't allow our people to come under the rule of butchers,'' General Mladic told a parade of Serb soldiers.
''As long as we exist, we will defend our graves and our homes ... the sacred Serb state must be preserved,'' he added, referring to the Serbs' collective dream of a ''Greater Serbia,'' which apparently has been tossed aside by President Milosevic.
Bosnian Serbs have drawn sustenance from an assessment made Monday by French commander of UN forces in Sarajevo, Gen. Jean-Rene Bachelet, who said the Dayton peace deal could prove ''unworkable'' because the status of Sarajevo was a last-minute improvisation that gives the Serbs a choice between a ''coffin or a suitcase.''
Thousands will flee the Serb suburbs before ceding the territory, he predicted, adding there was ''scarcely any doubt that before going the Serbs will implement a scorched-earth policy.''
Though General Bachelet was recalled immediately to Paris, his criticism rings true in Serb ears. The pitfalls of Serb defiance are cause for concern for senior military officers planning the largest NATO deployment in history.
Speaking of Mladic's warning, US Chairman of the Joints Chiefs of Staff Gen. John Shalikashvili said: ''it's clearly bothersome and worrisome, and we should not underestimate it.''
Though American officials have been given assurances by Mr. Karadzic that the safety of all NATO forces will be guaranteed, UN officials are long-used to such rhetoric from all of Bosnia's combatants, and are not convinced. ''One day Mladic says one thing, the next day Mladic says another. Dr. Karadzic changes his mind every hour,'' says UN spokesman in Sarajevo Alexander Ivanko.