BELGRADE, Yugoslavia -- Midnight in Belgrade. Instead of sleeping, thousands of motorists are heading for gasoline stations, hopeful that the lines will be shorter at this late hour. Usually they are a mile long instead of three, and the wait is only around two hours.
At Belgrade airport, would-be travelers are sent home. Yugoslav Airlines is canceling many flights because of a shortage of jet fuel.
Around kitchen tables, there is worried talk of the approach of winter -- and the lack of heating oil.
While the leaders of Serbia and Croatia continue to make and break cease-fire agreements, the undeclared war has crept up on Serbs over the past few weeks in the form of vital fuel shortages that are starting to affect everyone's lives.
Superficially, the shortages are reminiscent of those that drove Americans to desperation in the 1970s. But Yugoslavia's crisis is far deeper. Apart from freezing homes and the privations of a wrecked economy, rising popular discontent could force nationalist chieftains to a negotiating table. It also could severely undermine the government of Serbian President Slobodan Milosevic.
Such assessments are behind the emerging European Community policy, supported by the United States, that Yugoslavia's belligerents should be isolated and left to fight it out until complete exhaustion compels a settlement, according to senior diplomats here.
Only Slovenia, the tiny northwest province that declared independence in June, is excluded from this scenario. Slovenia, expected to be accorded diplomatic recognition in coming months, is likely to become part of a buffer zone designed to stop the unrest from spreading beyond Yugoslavia's borders.
At some point, in this view, the nationalist chieftains would have to come to terms with the catastrophic situation. So far, they seem more interested in their political objectives than in peace.
Some Western envoys believe that Croatia's President Franjo Tudjman has on several occasions deliberately provoked armed conflicts in an effort to force foreign military intervention.
"I have spent hours trying to dissuade Tudjman from his totally unfounded conviction that the West would send him military help," said one diplomat.
But Serbia's Mr. Milosevic is regarded by Western diplomats as the real "prince of darkness" in the war, unwilling to negotiate a fair political settlement and instead orchestrating campaigns of vast destruction of Croatia with the support of the Serbian-led Yugoslav military.
These diplomats now see the oil shortages as a way of bringing Mr. Milosevic to heel.
The unavailability and high cost of crude oil are only a part of Mr. Milosevic's problem. Its crux is that Serbia lacks the physical means to bring in more than one-fifth of its monthly requirement of 500,000 tons of crude.
The Serbian strongman found himself facing dire fuel shortages last month when, after a summer of mad gunplay, the Croatians decided to turn off the trans-Yugoslav pipeline. The Serbs, in turn, adopted a "beggar thy neighbor" attitude and imposed a blockade of Rijeka, the pipeline's starting port on the Adriatic. Both decisions meant more sacrifices for all and a further blow to a shattered economy.
The Milosevic government has commandeered old barges and all available road tankers in a desperate attempt to bring in sufficient quantities of Soviet and Libyan crude oil. The Serbs do produce some oil on the Pannonian Plain north of here, but not nearly enough to fill their needs. Yugoslavia's domestic crude production runs around 3.7 million tons annually, but Croatia's oil wells account for 75 percent of that.
The prospect of dramatic economic dislocations -- especially in Serbia, which is the most vulnerable -- is beginning to breed a siege mentality. In Croatia, shortages have not yet affected the man-in-the-car.
But here in Serbia, motorists are hoarding gasoline, keeping the reserves in their apartments, which are thus turned into potential firebombs. It is common for motorists to be told there is no gas at a station while the station's employees are busy scurrying with full cans to black-market buyers around the corner. There are rumors that rationing will be instituted soon. Two refiners are idled, and petrochemical industries face a bleak winter.
The disastrous situation is compounded by the collapse of Yugoslavia's banking, transportation, telecommunication and commerce. This month, the Soviet Union simply stopped natural gas deliveries to Serbia because it has not been paid. Serbian industrial energy consumers are in debt to the state-run Serbian gas company to the tune of about $600 million, roughly the same amount the distributor owes the Soviets.
The Soviet Union contracted to supply 5.5 million tons -- or more than a third of Yugoslavia's annual requirement -- in 1991, but, according to an Energy Ministry spokesman, it delivered "only half a million tons for the first six months of the year."
Few Soviet deliveries have come since August, when a group of Kremlin hard-liners attempted to depose President Mikhail S. Gorbachev. There is speculation that the halt was politically motivated, at least partly because the Serbs were among the few who publicly backed the plotters. But the fact is that the Soviet Union's economic situation is worse than Yugoslavia's.
Croatia's situation is somewhat better. It has substantial oil storage facilities in its major port cities. By contrast, oil arriving in Serbia's main port city in Bar, Montenegro, has to be offloaded directly onto railroad tankers. The Croats also have friendly neighbors in Italy, Austria and Hungary.
This leaves only the federal army with sufficient strategic reserves to keep itself afloat for at least six months, but winter and industrial unrest may prod even the generals to show more interest in peace than they have thus far.