By the time that Tripoli fell with surprising ease to rebel forces, NATO had flown more than 20,000 sorties during Operation Unified Protector. More than one third of these were strike missions, although weapons were not released on every sortie. The multibillion-dollar cost of the operation has been downplayed, but will likely be factored into post-conflict analysis of whether airpower was truly the decisive factor in removing the Gaddafi regime from power in Libya. The U.S. alone had spent $820 million on the operation by late August. It also reported the sale of weapons, fuel and technical assistance worth $220 million to allies. France was performing the greatest proportion of strike missions, at least until the aircraft carrier Charles De Gaulle was withdrawn for maintenance in early August. But the UK Royal Air Force claims to have flown the greatest proportion of “dynamic” strikes–those that were not preplanned before takeoff. Six other NATO countries have dropped weapons–Canada, Belgium, Denmark, Italy, Norway and the U.S. NATO briefers continue to insist that there were no “boots on the ground” to direct air strikes. But they acknowledged that some allies had inserted special forces under national command for this and other purposes. France, Qatar and the UK are reported to have equipped, trained and coordinated with rebel forces. Surveillance operations were stepped up during August when Italian Reaper and French Harfang (Heron) UAVs began flying over Libya from Amendola in Italy and Sigonella in Sicily, respectively. They were unarmed, but the U.S. confirmed in late August that its Predator UAVs had conducted 101 strike missions.