NATO planes buzzed over a United Nations "safe area" after Bosnian Serbs fired as many as 16 shells into the government-held town of Gorazde.
The planes were requested by the U.N. commander in Gorazde to deter further attacks, said U.N. spokesman Chris Gunness.Some of the Serb shells fired Tuesday hit Bosnian army positions, said another U.N. spokesman, Alexander Ivanko. There were no reports of casualties or damage.
In Sarajevo, Bosnian President Alija Izetbegovic renewed a proposal to demilitarize a 12.5-mile-wide band around the capital. Heavy weapons have been banned from the area for more than a year, although there have been many violations.
Izetbegovic coupled his proposal with a blunt warning that his Muslim-led government may have to fight a bloody battle to wrest control of the city from Serb foes.
He warned that if the Serbs "continue to attack our city and the international community doesn't protect it, our army will be called, together with our citizens, to liberate Sarajevo, regardless of the price."
"We have decided not to allow Sarajevo to enter the fourth winter under these circumstances," he said.
The United Nations has blamed the Serbs for recent mortar attacks on the center of Sarajevo, and accused them of targeting civilian areas with heavy weapons.
The city's airport remained closed Tuesday, preventing international mediators from traveling to Sarajevo. Bosnian Serbs refuse to promise not to fire on planes.
Despite the start of a government ban on public gatherings Tuesday, about 100 people attended the funeral of 17-year-old Maja Dzokic. She was killed by a mortar in downtown Sarajevo as she returned from a workout with her volleyball team.
At least 200,000 people are dead or missing in the Bosnian war since it broke out in April 1992.