The mountains of Afghanistan are among the most hazardous terrains for military operations. This topography has long enabled Afghans to successfully resist much more powerful conventional armies, as it did when Alexander the Great tried to conquer Afghanistan in the fourth century B.C. and again when Europeans undertook conquest attempts in the 1800s. After the Taliban were removed from power, they retreated to these mountains to stage their resistance against the new Afghan government and NATO forces.
Afghanistan's mountains, which run east to west through the country, are the westernmost extension of the Himalayan mountain system. The mountains consist of extremely elevated mountain ranges, such as the Safed Koh range along the Pakistani border and the Hindu Kush range to the north, which contain some of the highest peaks in the world and very rugged, steep topography. Though the desert climate means there is little vegetation to limit visibility, the complexity of the topography makes it difficult to observe or strike at militants hiding there, whether by ground or from the air.
The mountains that dominate central and northeastern Afghanistan break up the plains in the north and south of the country. While the Taliban have been active across Afghanistan, the mountain region along the Pakistani border is where most militant activity persists. This activity is mostly concentrated in Wardak, Logar, Paktia, Nangarhar, Kunar and Laghman provinces, south and east of Kabul. Militancy has also been on the rise in Badakhshan province in the northeastern corner of the country. Until around 2010 the main threat of Taliban forces was in the southern plain, in Helmand and Kandahar provinces, but the lack of complex terrain allowed NATO forces there to be much more effective than those in the mountains during the U.S. troop surge. Since the mountains provide more protection for the Taliban than the plains, NATO troops have had to focus their operations in this area, though they remain active throughout Afghanistan, including in its southern provinces.This mountainous terrain is also important due to its proximity to the Pakistani border. Political borders can cause a major interdicting factor in military operations against militants. The need to coordinate operations with separate actors, as well as the inability to operate across the border in the territory of an allied sovereign state without causing diplomatic incidents, affects operations on the ground and can create areas of lesser resistance that allow militants to seek refuge or supplies across borders. Militants' seeking refuge in Pakistan is one of the main factors behind U.S. unmanned aerial vehicle operations across Afghanistan's borders.
Pashtun tribes and other Afghan ethnic groups on both sides of the border also help make the Pakistani border a haven for militants. This population can support militant activity across the border and enables those that cross from one side to the other to easily blend into the local population. On the Pakistani side of the border, there are also a number of large refugee camps that have been a great source for Taliban recruitment and shelter or medical care for militants. The ability to execute precise unmanned aerial vehicle strikes against suspected militant leaders, such as those of the Haqqani network, is greatly limited by the militants' ability to take cover or hide among the population. This also allows them to set up bases and operate in populated areas, where they can depend on familial and logistics support.
The prime target of Kabul is also located within these mountains, allowing militants to operate in and around the city. Since many targets are within the same terrain that protects the militants, they can attack their adversaries without leaving cover. In addition, the mountainous provinces south and east of Kabul, where Taliban militants are currently concentrated, make up the main supply line leading directly from Pakistan into Kabul. However, this area also presents a challenge to the Taliban because it forces them to maneuver tribal relations in order to guarantee access throughout the region. For this they need to work with and often pay tolls to local tribes, whose allegiances can change over time. As many advantages as the mountainous terrain may provide, militants and local governments still must navigate the intricate web of tribal relations in the region.
Winter adds an extra element of hardship to the Afghan mountain terrain. From December to April, the temperature in much of this area drops below freezing and snowfall limits movement during part of the winter, reducing supply lines in the central and northern regions of Afghanistan. After the winter period, thawing snows and storms can cause flash floods. The region's extremely limited transportation infrastructure makes it especially vulnerable to these natural phenomena.
These meteorological constraints are as applicable to the NATO forces as they are to the Taliban militants. Taliban forces disperse and, while some do remain in the mountains, others go home to farm or cross the border into Pakistan, returning in the spring to recommence the insurgency around late March and April. NATO forces become static throughout the winter season, due to the difficulty of conducting patrols or maneuvers. During the winter usually only special operations forces conduct offensive actions, but even these slow down because the militants are less active.
Though the value of this terrain is similar to other mountainous regions used by militants in other countries, the great area of the Afghan mountains enhances their ability to provide refuge for militants. The region's elevation and distance from the equator causes it to have a harsh winter that introduces temporal constraints in addition to the spatial constraints on operations against militants. The downtime during the winter gives the Taliban an opportunity to reorganize and continue the insurgency. The combination of protective physical geography and temporal constraints enhances the ability of a guerilla-styled Taliban force to resist, and continue to remain effective against, the conventional armed forces trying to dislodge them.