Beginning several months later than fighting in the republics of Slovenia and Croatia, the Bosnian civil war was the most brutal chapter in the breakup of Yugoslavia. On February 29, 1992, the multiethnic republic of Bosnia and Herzegovina, where Catholic Croats, Orthodox Serbs, and Muslim Slavs lived side by side, passed a referendum for independence -- but not all Bosnian Serbs agreed. Under the guise of protecting the Serb minority in Bosnia, Serbian leaders like Slobodan Milosevic (1941-) channeled arms and military support to them. In spring 1992, for example, the federal army, dominated by Serbs, shelled Croats and Muslims in Sarajevo, the Bosnian capital. Foreign governments responded with sanctions (not always tightly enforced) to keep fuel and weapons from Serbia, which had (in April 1992) joined the republic of Montenegro in a newer, smaller Yugoslavia. Bosnian Serb guerrillas carried out deadly campaigns of "ethnic cleansing," massacring members of other ethnic groups or expelling them from their homes to create exclusively Serb areas. Attacks on civilians and international relief workers disrupted supplies of food and other necessities just when such aid was most crucial: in what became the worst refugee crisis in Europe since World War II, millions of Bosnians (and Croatians) had been driven from their homes by July 1992. Alarmed by ethnic cleansing and other human rights abuses (which Croats and Muslims also engaged in, though to a lesser extent than did the Serbs), the United Nations resolved to punish such war crimes. In early 1994 the fierce three-way fighting became a war between two sides. In February and March the Muslims and Croats in Bosnia called a truce and formed a confederation, which in August agreed to a plan (developed by the United States, Russia, Britain, France and Germany) for a 51-49 split of Bosnia, with the Serbs getting the lesser percentage. Despite the Muslim-Croat alliance, the peace proposal, and an ongoing arms embargo against all combatants (an embargo criticized abroad for maintaining Bosnian Serb dominance in weaponry), the fighting did not stop. In 1994 and 1995 Bosnian Serbs massacred residents in Sarajevo, Srebenica, and other cities that the United Nations had in May 1993 deemed "safe havens" for Muslim civilians. Neither NATO air strikes (beginning in April 1994) nor the cutoff of supplies from Serbia (as of August 1994) nor the cutoff of supplies from Serbia (as of August 1994) deterred the Bosnian Serbs, who blocked convoys of humanitarian aid and detained some of the 24,000 UN troops intended to stop hostilities. Like their allies in Serbia, the Bosnian Serbs wanted to unite all Serb-held lands of the former Yugoslavia. By September 1995, however, the Muslim-Croat alliance's conquests had reduced Serb-held territory in Bosnia from over two-thirds to just under one-half -- the percentage allocated in the peace plan for the Serb autonomous region. On December 14, 1995, the leaders of Bosnia, Croatia, and Serbia signed the Dayton peace accords, officially ending the wars in Bosnia and Croatia after about 250,000 people had died and more than 3 million others became refugees. NATO troops numbering 60,000 entered Bosnia to enforce the accords. In early 1998 about 30,000 NATO peacekeepers were still in Bosnia, which remained scarred by war and divided between the Muslim-Croat confederation and the Bosnian Serb region. Dozens of suspected war criminals had been indicted by the UN tribunal, including Bosnian Serb leader Radovan Karadzic (1945-) (who had resigned in June 1996), although many had not been arrested or tried.