The Afghan Border Force (ABF) was responsible for security of Afghanistan's border area with neighboring countries extending up to 30 miles (48 km) into the interior and formed part of the Afghan National Army. In December 2017, most of the Afghan Border Police (ABP) personnel of the Afghan National Police were transferred to the Afghan National Army to form the Afghan Border Force. The ABP retained 4,000 personnel for customs operations at border crossings and international airports such as checking documents of foreigners entering the country or deporting them.