During the mid-1960s, the United States Army initiated the Advanced Aerial Fire Support System (AAFSS) program, which led to the development of the Lockheed AH-56 Cheyenne for use in the anti-tank gunship role. The US Army pursued the AH-1G HueyCobra as an "interim type" for the "jungle fighting" role. However, the Army's broader concern was the task of protecting Western Europe from the legions of Warsaw Pact armor to the east. The main scenario used by NATO throughout the Cold War was that, if the Soviet Union and Warsaw Pact forces were to conduct a massive tank offensive attack on Western Europe, they would probably cross either the Fulda Gap (capturing Frankfurt first and then aiming for the westward bend of the Rhine south of Wiesbaden: a total distance of just 85 miles), or cross the North German Plain (see map). The Advanced Attack Helicopter was conceived from the need to defend against such an attack.