The U.S. Air Force in 2002 requested permission to fly a KC-10 tanker across Austrian airspace, but the Austrians became suspicious of the request. A fighter patrol sent by the Austrian Air Force found two F-117 stealth fighters accompanying the tanker. The single approved plane was actually flying with two more unapproved planes. The Austrian air force sent two Swedish-made Draken fighter jets to investigate. The aircraft number for the DC-10 was actually assigned to an aerial refueling aircraft. The flight registration was reportedly changed twice during short notice. The incident occurred during the time the Air Force was involved in combat missions over Afghanistan and the buildup of military forces in the Persian Gulf region led to the invasion of Iraq.