An American plane landed in Sarajevo on Saturday, bringing badly needed food and the promise that a full-fledged international airlift would resume after a monthlong suspension.
Bad weather, however, forced a second U.S. aircraft to divert to the Croatian capital, Zagreb, on two separate, unsuccessful attempts to deliver supplies, U.N. officials at Zagreb airport said.
Relief officials fear Bosnia's traditionally harsh winter could claim hundreds of thousands of lives without adequate supplies of food, fuel and materials to repair war-damaged homes.
Meanwhile, the commander of the Bosnian Serbs' air force said he would be "capitulating" if he accepted a flight ban over the republic, as suggested by the West.
On Saturday, Bosnian Serb aircraft bombarded Tesanj and Zenica, both northwest of Sarajevo, Croatian radio reported, citing Bosnian radio.
Almost daily reports of Serb air raids have led Western allies to urge the United Nations to set up a "no-fly" zone for combat flights over Bosnia. President Bush said Friday he backed the proposal and promised to enforce it with military action if necessary.
The growing support for a flight ban is a departure from the West's earlier reluctance to authorize military force for anything but the protection of relief supplies. The international airlift to besieged Sarajevo was suspended Sept. 3 after an Italian relief plane was downed, killing all four crew members.
Bosnian Serb officials vehemently rejected the proposed flight prohibition.
"If the ban is implemented, we will consider the United States as an aggressor and an occupier in Bosnia," said Biljana Plavsic, the top aide to Bosnian Serb leader Radovan Karadzic.
The Serbs have about 40 aircraft the Yugoslav army left when it withdrew from Bosnia earlier this year.
Peace envoys in Geneva have obtained an agreement from the major warring factions to demilitarize parts of Sarajevo.