The armed incidents of early 1991 escalated into an all-out war over the summer, with fronts formed around the areas of the breakaway SAO Krajina. The JNA had disarmed the Territorial Units of Slovenia and Croatia prior to the declaration of independence, at the behest of Serbian President Slobodan Milošević. This was aggravated further by an arms embargo, imposed by the UN on Yugoslavia. The JNA was ostensibly ideologically unitarian, but its officer corps was predominantly staffed by Serbs or Montenegrins (70 percent). As a result, the JNA opposed Croatian independence and sided with the Croatian Serb rebels. The Croatian Serb rebels were unaffected by the embargo as they had the support of and access to supplies of the JNA. By mid-July 1991, the JNA moved an estimated 70,000 troops to Croatia. The fighting rapidly escalated, eventually spanning hundreds of square kilometers from western Slavonia through Banija to Dalmatia.