Serbia blocked Croatia's Stipe Mesic from taking over as president on Wednesday, leaving Yugoslavia poised for civil war without a head of state or commander of the armed forces.
In the highly charged atmosphere of ethnic hostility, the political slap in the face dealt to Croatia intensified the risk of new outbreaks of the violence that has already killed at least 19 people this month.
The blockade against Mesic plunged Yugoslavia into its second leadership crisis this year and increased the chances of a military takeover and breakup of the country, which was formed from rival Balkan states in 1918.
Mesic had warned a day earlier that if Serbia moved to prevent him from taking his turn in the rotating leadership, Croatia would secede from Yugoslavia.
But Croatian leaders made no immediate declarations about how they will proceed after the rebuff, perhaps in the hope that a second session of the deadlocked presidency today might clear the obstacles to Mesic's succession.
"It's not possible that I will not become president," Mesic told Zagreb television. "Those who voted against me must think over what that means. Those who voted against me are breaking up Yugoslavia."
He said he is confident of winning endorsement once his Serbian colleagues have reconsidered the consequences of their actions overnight.
"Since it is customary here in Belgrade to hand in and then repeal resignations, there is a possibility for the vote to change after a while," Mesic said after his unprecedented rejection by the ruling body.
He referred to the March resignation of outgoing President Borisav Jovic of Serbia, a hard-line Communist who tried to provoke a military coup d'etat by stripping the eight-man presidency of the quorum it needs to issue directives.
When the army failed to take power, Jovic was forced to return to his post five days later.
Some speculated that Serbia would back off from an action expected to draw broad international denunciation. The largest of Yugoslavia's six republics, Serbia has already succeeded in tarnishing Croatia's image. By blocking the ascension of Mesic, a 56-year-old former political prisoner who would be the federation's first non-Communist head of state, Serbia has demonstrated its ability to circumvent the authority of its historical adversary.
But others saw the move as a sign that Serbia's Communist leadership would rather expose Yugoslavia to a bloody fratricide than risk being forced out of power by a nationalist outcry for allowing a Croat to assume the federation's highest office.
"The political side of this is terrifying," said Macedonia's delegate to the collective presidency, Vasil Tupurkovski. "It ruins the concept of equality among the republics."
Tupurkovski said he fears that Croatia will pull out of the presidency and that a peacekeeping accord hammered out by the republics last week will fall apart as radicals on both sides take matters into their own hands in the absence of any leadership.
"This is absolutely the top of the crisis, with unforeseeable consequences," Tupurkovski said in an interview. "I'm struck by the irrationality and irresponsibility" of those who refused to approve the succession of Mesic.
According to the 1974 federal constitution, the head of state rotates annually among the eight-member collective leadership representing Yugoslavia's six republics and two provinces.
But Serbia has three of the eight votes by virtue of its subjugation of the Kosovo and Vojvodina provinces. The neighboring republic of Montenegro, which is predominantly populated by Serbs, usually votes along with the Serbian delegates.
All three Serbian presidential delegates voted against Mesic and Montenegro abstained, leaving the final vote 4 to 3 in favor of the constitutionally mandated rotation. Five votes are needed for any decision of the presidency.
The constitutional procedure calling for automatic annual rotation of leadership appears to conflict with the presidency's practice of voting on each new leader. That left open a question of interpretation.
Slovenian sources said they recognize Mesic as president despite the vote.
The abstention of Montenegrin delegate Momir Bulatovic also left open the possibility that he would change his mind later and endorse Mesic, although Montenegro has never been known to defect from the views espoused by dominant Serbia.
Jovic, whose term as president expired at midnight Wednesday, said he could not back Mesic because it would trigger a revolt by Serbian nationalists that would threaten the leadership of Serbian President Slobodan Milosevic, according to a source who took part in the presidential session.
Milosevic is blamed for whipping up Serbian nationalism to a fever pitch by insisting that all Serbs live in one country. His supporters and members of radical Serbian political movements have vowed to forcibly prevent the secession of Croatia, where 600,000 ethnic Serbs live.
Many of the armed Serbian bands challenging police for control of Serbian villages in Croatia have been linked to Milosevic and radicals seeking to recover all territory ruled by Serbia in the past.
Balkan borders shifted for centuries as people and property were turned into the spoils of war, until Yugoslavia was formed after World War I from regions long ruled by the great empires of Ottoman Turkey and Austria-Hungary.
During his term as president, Jovic--a staunch Milosevic ally--used the Serbian-commanded federal army to intercede in the ethnic clashes stirred up as armed Serbian civilians have tried to take over local police stations in Croatia.
Army tanks and troops have been widely deployed to potential trouble spots in Croatia and Bosnia-Herzegovina, ostensibly to prevent further bloodshed.
But Croatian authorities in Zagreb claim that the deployments actually form a military cordon along what Serbia would like to be the northern border of an enlarged state to incorporate Serbs living in neighboring republics.
A Croatian declaration of independence would probably touch off violent revolt among Serbs in the occupied region, while imposition of martial law would likely prompt Croatian police and reservists to try to reclaim the military-controlled regions of their republic.
According to official sources in Belgrade, Serbia was warned by the U.S. government and European diplomats that Yugoslavia would face a cutoff of Western aid if Mesic was prevented from assuming the presidency.
U.S. Ambassador Warren Zimmermann met with Milosevic on Friday and was assured "that Jovic would step down and normal rotation would take place," said an American source who spoke on condition of anonymity.
"There should be no misunderstanding what this all means," the source said, referring to the rejection of Mesic. "It is an effort by the Serbian leadership to disrupt the normal rotation of the presidency. Coming at a time of extreme tension, it can only be seen as highly irresponsible. There are fingers on the trigger all over this place."