Major's premiership coincided with the collapse of Yugoslavia and the resulting war in Bosnia and Herzegovina (and parts of Croatia). Tensions between the constituent republics of Yugoslavia had been building since the death of President Josep Broz Tito in 1980, exacerbated by the political uncertainty caused by the collapse of Communism across Eastern Europe in the period 1989–91. In June 1991 both Slovenia and Croatia declared independence; whilst the Serb-dominated central government in Belgrade let the almost homogeneous Slovenia leave after only a brief war, the situation in Croatia, parts of which contained large numbers of ethnic Serbs, was much more contested. The EU, at Germany's insistence, recognised the independence of the two states in December 1991. War broke out between Serbia (led by the nationalist Slobodan Milošević) and Croatia (ruled by Franjo Tuđman) over the Serb-populated region of Slavonia region in north-east Croatia, prompting the UN to send in a peacekeeping force (UNPROFOR). The fiercest fighting however occurred following the declaration of independence by Bosnia and Herzegovina under President Alija Izetbegović on 6 April 1991; the mountainous republic's population was split between Bosnian Serbs, Bosnian Croats and Bosnian Muslims (or 'Bosniaks'), and full-scale civil war broke out between them, with the Bosnian Croats and Bosnian Serbs backed by Tuđman and Milošević respectively. The war caught Europe and the world unawares, and shocking scenes of POW camps (likened by some to Nazi concentration camps), huge refugee flows and campaigns of ethnic cleansing began to be broadcast over the world, leading to calls for intervention.