the first time. The Bosnian Serbs were accused of the bombing but denied responsibility. On 31 March, a resolution was voted authorising the nations contributing to UNPROFOR to take "all necessary measures" to prevent military flights from the belligerents in the no-flight zones ("Operation Deny Flight"). French, Dutch, and American airplanes were deployed to enforce the resolution. In total, until 1 December 1994, 3317 violations were observed. On 28 February 1994, four military aircraft were shot down by NATO fighter jets over Bosnia and Herzegovina. Safe areas From March 1993, Serb paramilitary units killed a great number of civilians, destroyed habitations, prevented the UNHCR from delivering humanitarian aid, and forced thousands of Bosnian refugees to flee to the town of Srebrenica. As many as 30 to 40 persons per day were dying from military action, starvation, exposure to cold or lack of medical treatment. Resolution 819 attempted to address this issue by declaring Srebrenica a "Safe Area". Resolution 836 authorized UNPROFOR "acting in self-defense, to take the necessary measures, including the use of force, in reply to bombardments against the safe areas by any of the parties or to armed incursion into them or in the event of any deliberate obstruction in or around those areas to the freedom of movement of UNPROFOR, or of protected humanitarian convoys" . To implement the deterrence, around 7,600 reinforcements were sent and air support was organised in coordination with NATO. War in Bosnia In May 1993, intense fighting broke out in Central Bosnia between Bosniaks and Bosnian Croats. Croat paramilitary forces, committed atrocities against Serbs and Bosnians, such as the massacre in the village of Ahmići, on 16 April 1993. Tihomir Blaškić, an officer of the Croat HVO army formation, was tried and convicted at the ICTY over his responsibility for this massacre. Blaškić served almost nine years in prison before the appeals panel acquitted him of most of the charges in July 2004. The defence proved he did not command all the HVO units in the area or any paramilitary units. On 24 September, the Security Council was informed by the Croatian Government that if the mandate of UNPROFOR was not amended to promote energetic implementation of the relevant resolutions of the Security Council, Croatia would be forced to request UNPROFOR to leave the country no later than 30 November 1993. Subsequent redefinition of the mandate occurred. At the end of the