Tora Bora (, "Black Cave") is a cave complex, part of the Spin Ghar (White Mountains) mountain range of eastern Afghanistan. It is situated in the Pachir Aw Agam District of Nangarhar, approximately west of the Khyber Pass and north of the border of the Khyber Pakhtunkhwa province in Pakistan. Tora Bora and the surrounding Spin Ghar range had natural caverns formed by streams eating into the limestone, that had later been expanded into a CIA-financed complex built for the Afghan mujahideen. Tora Bora was known to be a stronghold location of the Afghan mujahideen, used by military forces against the Soviet Union during the 1980s. Geology The geology of Tora Bora is predominantly metamorphic gneiss and schist. History Military base In October - November 1980, during Operation "Shkval", this complex was taken by the "Kaskad" special forces unit of the USSR KGB, together with the 66th motorized rifle brigade of the 40th Army of the Soviet troops in Afghanistan. As Colonel Valentin Gerasimenko wrote about the first assault, “By that time, Tora Bora was still a little-known, but already covered with a veil of mystery, the base of the Dushmans. Only later will it surpass the Panjshir Valley in its glory and fame, in the number of assaults and destruction”. June 18–19, 1981 - in the province of Nangarhar, 85 km south of Jalalabad, in the area of the Afghan-Pakistani border, units of the Soviet 66th motorized rifle brigade and part of the Afghan 11th Jalalabad infantry division take the fortified area of the Mujahideen Tora Bora. July 22–29, 1983 - operation in Tora-Bora of the 66th motorized rifle brigade. The base at Tora Bora was developed as a CIA-financed complex built for the Mujahideen following the 1979 Soviet invasion of Afghanistan, and has been described by the western media as an "impregnable cave fortress" housing 2,000 men complete with a hospital, a hydroelectric power plant, offices, a hotel, arms and ammunition stores, roads large enough to drive a tank into, and sophisticated tunnel, and ventilation systems. During the U.S. invasion of Afghanistan, the cave complex was one of the strongholds of the Taliban and Al-Qaeda, according to United States Secretary of Defense Donald Rumsfeld. It was the location of the December 2001 Battle of Tora Bora, and suspected hideout of Al-Qaeda leader Osama bin Laden. It was reported that in 2007, U.S. intelligence suspected bin Laden planned to