On 4 August 1995, the CAF had at its disposal 17 MiG-21s, five attack and nine transport helicopters, three transport airplanes and two reconnaissance aircraft. On that first day of the operation, thirteen MiG-21s were used to destroy or disable six targets in the Gospić and Zagreb Corps AORs, at the cost of one severely and three slightly damaged jets. The same day, three Mi-8s were used for medical evacuation. US Navy EA-6Bs and F/A-18s on patrol as part of Operation Deny Flight fired on ARSK surface-to-air missile (SAM) sites at Udbina and Knin as SAM radars locked onto the jets. A few sources claim that they were deployed as a deterrent as the UN troops came under HV fire, and a subsequent UN Security Council report only notes that the deployment was a result of the deterioration of the military situation and resulting low security of the peacekeepers in the area. Also on 4 August, the RSK 105th Aviation Brigade based at Udbina, deployed helicopters against the Croatian special police on Velebit Mountain and against targets in the Gospić area virtually to no effect.