AS sirens howl over this coal-mining town along the Slovene River, air-raid wardens hustle terrified children from a passenger train into shelters."Slovenia used to be the most peaceful spot in the world," says Tina Music, one of two women escorting 60 children to a language school program in London. "I just can't believe it has come to this." A few miles to the southeast, near the village of Brezice, farmers and passersby gather to gawk at burned-out Yugoslav Army tanks still smoldering after fierce fighting with Slovene defense forces a few hours before. A wrecked Soviet-designed T-72 tank - gutted to the chassis, its gun turret gone - blocks the road. Nearby, souvenir hunters sift through charred debris, collecting shell casings and chunks of steel from a shattered armored personnel carrier. Although federal troops have since withdrawn from the area around Brezice, residents of this hamlet say they have little faith in a new and tenuous cease-fire. "They'll be back," says Ivan Duric, watching a column of about 30 Army tanks withdrawing to barracks outside Zagreb, the capital of Croatia. The uneasy cease-fire held overnight Wednesday despite concerns of an impending Yugoslav Army attack. In Belgrade, members of Yugoslavia's collective federal presidency held a meeting Thursday, but Slovenia's representative did not attend. And it is reported that troops with 180 tanks and other armored vehicles have been ordered north from their barracks in Belgrade. Fighting has raged here since Slovenia and neighboring Croatia declared independence June 25. The Serbian-dominated Army intervened after Slovene militia seized border posts. The showdown between Slovenia and the federal Army is part of a complex web of ethnic rivalries, militant nationalism, and ideological disputes that threaten the existence of this nation of six republics and two provinces. A European Community-brokered truce fell apart on Tuesday a few hours after the Slovenes demanded that surrounded federal troops give up their weapons before withdrawing. The demand, viewed as calling for a humiliating surrender, enraged the military brass in Belgrade and led to large-scale retaliatory assaults. The Army chief of staff, hard-line Gen. Blagoje Adzic, warned that such conditions would only escalate fighting. "We have to accept war," General Adzic said, "because the alternatives of surrender or treason do not exist for us." He vowed that the Army would "stop this arrogant [Slovene] behavior and bring everything under control." EC foreign ministers are to meet in emergency session today at The Hague to discuss the crisis. Croatia, larger and stronger than Slovenia, has so far avoided widespread combat, partly because its independence actions have been less far-reaching. An attack on Croatia would also certainly increase ethnic fighting. More than 40 people have died in violence inside Serb-dominated regions of Croatia since May. Yugoslavia's armed forces are dominated by pro-communist Serbian officers committed to preserving the multi-ethnic nation's current borders. ADZIC'S comments heightened speculation that the Army was acting on its own to suppress Slovenia's drive for independence - and that neither the presidency nor Premier Ante Markovic had any control over the military. For several days, the Army has appeared to ignore the orders of Stipe Mesic, chairman of the eight-member collective presidency, which is supposed to control the armed forces. Adzic's warnings, for example, were delivered on national television while Mesic was on a peace mission to Slovenia. Gen. Andrija Raseta, deputy commander of federal forces in Slovenia, said the military remained under civilian authority. But Slovenian and Croatian officials say they are nervous because federal military commanders have sent conflicting signals, ordering the Army to hold fire unless attacked but at the same time dispatching troops and tanks toward Croatia and Slovenia. Croatian Defense Minister Sime Djodan says the armored advance suggests that Army generals are split over the cease-fire. Other observers believe the move is a show of force to intimidate the breakaway republics. Serbia vehemently opposes the independence drives of Slovenia and Croatia, which turned to secession after they failed to transform Yugoslavia into a loose association of sovereign states. Croatian leaders have accused Serbia "and some Army circles of helping the Army of Serbian terrorists in Croatia." Although the Army has experienced setbacks in Slovenia, the republic's militia forces would not be able to withstand a major federal offensive. But Slovenia's fledgling territorial defense has proved extremely effective in fighting guerrilla actions, which could bog down federal units for months if conflict persists. Slovenes say the Army's behavior has only increased their resolve to pursue an independent course, although a truce would put further steps on hold. And they remain defiant. Says Judita Zver, an architect in Ljubljana: "We have won, even if they send more troops and occupy us. We have shown to the world we have defended our territory with honor." Lt. Dusan Soprek, a tank commander with withdrawing federal forces outside Brezice, just hopes the fighting is over. "We want peace. We want to go home."