The country's transportation infrastructure was severely damaged during the first and second Congo Wars, and it has not yet recovered. In particular in the north and east of the country, many vehicles were destroyed or taken over by militias, and the fuel supply system was also severely impacted. As a result, private and commercial road transport is virtually nonexistent outside of Kinshasa, Matadi, and Lubumbashi, and traffic is sparse even on roads that are in good condition. The United Nations, aid organizations, the DRC government, and a few larger businesses, including those in the mining and energy industries, operate the few vehicles that are utilized outside of these cities. Compared to similar images of towns in neighboring nations, high-resolution satellite images available online show large cities like Bukavu, Butembo, and Kikwit virtually traffic-free. Air travel is the only viable option for moving between many locations within the country. Air travel is preferred to ground transportation by the Congolese government, the United Nations, aid organizations, and large corporations. Compared to other African nations, the DRC has a large number of small domestic airlines and air charter companies, and the United Nations has a large fleet of aircraft and helicopters. In the east, some paved roads that have been cut off by collapsed bridges or sections that are impassable have been converted into airstrips for the purpose of transporting heavy minerals.