As the Yugoslav People's Army (JNA) increasingly supported the SAO Krajina, the Croatian Police were unable to cope. Thus, the Croatian National Guard (ZNG) was formed in May 1991. The development of the military of Croatia was hampered by a UN arms embargo introduced in September, while the military conflict in Croatia continued to escalate—the Battle of Vukovar started on 26 August. By the end of August the fighting intensified in Lika as well, specifically as the Battle of Gospić continued through much of September.