SARAJEVO, BOSNIA-HERZEGOVINA — LIKE a hulking steel predator, the Serbian armored car growled to a halt, swiveled its turret, and unleashed a storm of cannon rounds into a row of shell-torn townhouses facing Sarajevo airport.
Serbian gunners entrenched in the airport complex joined the fusillade with machine gun and mortar fire, intent on silencing sniper attacks from the houses by members of the city's predominantly Muslim Slav defense force.
Plumes of smoke rose from burning cars, and shells and ricocheting bullets whined overhead.
"This is crazy," muttered a soldier of the United Nations Protection Force (UNPROFOR), as shock waves washed over his bunker at the entrance of the airport's main terminal Friday.
A day later, he and 82 other UN personnel were withdrawn to the UNPROFOR headquarters near the city center as their commander, Canadian Army Gen. Lewis MacKenzie, suspended efforts to reopen the airport to humanitarian aid flights because both sides failed to observe a June 5 cease-fire.
At almost the same time, the republic's seven-member presidency of Muslim Slavs, Croats, and loyalist Serbs declared a "state of war" and a general mobilization of draft-aged men.
The declaration and the UNPROFOR withdrawal from the havoc around the airport underscored the continuing descent of Europe's newest country into anarchy, unchecked by the imposition of UN sanctions against Serbia and Montenegro for supporting the Serbian offensive.
"The little glimmer of hope that came with the latest cease-fire last Monday turned out to be an illusion. People have become crazier, hungrier, and angrier," said a Belgrade-based Western diplomat who tracks developments in Bosnia-Herzegovnia.
Combat rages without respite across the republic, adding to the tragedy of the more than 7,200 people dead, 25,000 injured, and 1.3 million driven from their homes in three months.
Hunger is growing in Sarajevo, where the desperation of the estimated 300,000 people trapped by a Serbian siege deepened with General MacKenzie's decision to suspend UNPROFOR's attempt to reopen the airport for food and medicine deliveries.
"People began screaming and crying when they heard about it," said a resident of Dobrinja, a sprawling residential colony opposite Sarajevo airport, encircled by Serbian fighters and tanks.
The situation has been further complicated by the maneuverings of neighboring Croatia, whose right-wing president, Franjo Tudjman, earlier this month agreed to a military cooperation accord with his Bosnian counterpart, Alia Izetbegovic.
Western diplomats and other analysts expressed alarm, saying they believed that Mr. Tudjman saw the pact as an opportunity to exploit the worsening plight of Mr. Izetbegovic's government and hard-pressed defense forces.
HE accord, they said, justified the presence in parts of the republic of significant numbers of well-armed regular forces infiltrated from Croatia.
"I don't think the Croats will resist the temptation of biting off large chunks of Bosnian territory," said Milos Vasic, the military affairs writer of Belgrade's Vreme magazine.
"The war is quickly becoming one between Serbs and Croats, with the Muslim Slavs caught in the middle," said Mr. Vasic.
Large concentrations of regular Croatian Army forces have already helped turn the tide in the overwhelmingly Croatian region of Western Herzegovina, driving Serbian units out of the town of Mostar in a headlong retreat.
"Croatian armed forces from the republic of Croatia are making a very good offensive and taking our territory down there," Serbian Democratic Party president Radovan Karadzic acknowledged in an interview in his stronghold east of Sarajevo.
The Croatian goal, Vasic said, is to break the Serbian stranglehold on Croatia's historic city of Dubrovnik, which sits on a tiny sliver of Adriatic coastline bordering Eastern Herzegovina.
Other evidence of Croatian territorial aspirations were clashes over the weekend between Croatian paramilitary units and Muslim Slav fighters around the central town Travnik, where there is a large Croatian minority.
Tudjman's nationalist regime denies having territorial claims on Bosnia-Herzegovina, asserting that the pact with Izetbegovic embodied its recognition of the neighboring republic's independence. But, Vasic said, Tudjman is desperate to reap the political benefits of territorial gains after losing one-third of Croatia to Serbian forces in its own war of independence last summer.
The belief of a greater involvement by Croatia has strengthened Serbian resolve to carve out a self-declared Serbian state.
"The Croats are just using the Muslims for now. But after they drive the Serbs out of Bosnia, they will turn on the Muslims," contended Col. Kamnen Zarkovic, the commandant of the Serbian Democratic Party-held former Yugoslav Army base, which is in the Sarajevo suburb of Lukavica.
"We are fighting for our country, our future, for our people," declared a Serbian guerrilla, his face caked with sweat-streaked camouflage paint, as he and his commando unit rested at Sarajevo airport from a night of Combat.
"The war will not end until there are new borders," he said.