the United States Air Force for expanding Area 51. According to the judge, the land that overlooked the base was taken to address security and safety concerns connected with their training and testing. Legal status U.S. government's positions on Area 51 The United States government has provided minimal information regarding Area 51. The area surrounding the lake is permanently off-limits to both civilian and normal military air traffic. Security clearances are checked regularly; cameras and weaponry are not allowed. Even military pilots training in the NAFR risk disciplinary action if they stray into the exclusionary "box" surrounding Groom's airspace. Surveillance is supplemented using buried motion sensors. Area 51 is a common destination for Janet, a small fleet of passenger aircraft operated on behalf of the Air Force to transport military personnel, primarily from Harry Reid International Airport. The United States Geological Survey (USGS) topographic map for the area only shows the long-disused Groom Mine, but USGS aerial photographs of the site in 1959 and 1968 were publicly available. A civil aviation chart published by the Nevada Department of Transportation shows a large restricted area, defined as part of the Nellis restricted airspace. The National Atlas shows the area as lying within the Nellis Air Force Base. There are higher resolution and newer images available from other satellite imagery providers, including Russian providers and the IKONOS. These show the runway markings, base facilities, aircraft, and vehicles. In 1998 USAF officially acknowledged the site's existence. On 25 June 2013, the CIA released an official history of the U-2 and OXCART projects which acknowledged that the U-2 was tested at Area 51, in response to a Freedom of Information Act request submitted in 2005 by Jeffrey T. Richelson of George Washington University's National Security Archive. It contains numerous references to Area 51 and Groom Lake, along with a map of the area. Media reports stated that releasing the CIA history was the first governmental acknowledgement of Area 51's existence; rather, it was the first official acknowledgement of specific activity at the site. Environmental lawsuit In 1994, five unnamed civilian contractors and the widows of contractors Walter Kasza and Robert Frost sued the Air Force and the United States Environmental Protection Agency. They alleged that they had been present when large quantities of unknown chemicals had been burned in open pits and trenches at Groom. Rutgers University biochemists analyzed biopsies from the complainants and