Narrow mountain roads are choked with snow. Foul weather would blind many of NATO's frontline aircraft, taking away NATO's technological superiority. Everything will be complicated by the cold. Miles of white netting will be required to shroud olive-drab military gear. Snow fouls weapons, and cold air produces large clouds of condensation when the weapons are fired, making it easy to pinpoint the shooter.
Helicopter rotor blades whip up mini-blizzards that can blind pilots.
But the biggest fear is that the retreating forces will have to fight their way out. Commanders from both Bosnian and Serbian camps crave the U.N.'s light tanks and armored vehicles, which the peacekeepers have vowed to take with them. The Serbs could fire down on the departing columns as they move along the mountain roads. Snipers and artillery could harass convoys ambushed at roadblocks. There are dozens of bridges and tunnels along the way from Sarajevo to the coast, all vulnerable to sabotage.