Since 1949, a series of armed skirmishes and firefights have occurred along the Durand Line (the Afghanistan–Pakistan border) between the Afghan National Security Forces and the Pakistan Armed Forces. The latest hostilities, which are ongoing, began with the overthrow of the Taliban government.
Hostilities existed between Afghanistan and the newly independent Pakistan since 1947, when Afghanistan became the only country to vote against the admission of Pakistan to the United Nations. Afghanistan advocated the independence of Pakistan's Khyber Pakhtunkhwa to form Pashtunistan, although the region's predominant Pashtun population had voted overwhelmingly in favor of Pakistan in the referendum held in July 1947. 289,244 (99.02%) votes were cast in favor of Pakistan. Afghan nationalists pressed for an independent state to be called Pashtunistan but the idea became unpopular. The Balochistan province of Pakistan was also included in the Greater Pastunistan definition to gain access to the Arabian sea in case Pakistan failed as a state, as Afghanistan had expected.
The International border between the British Raj and Afghanistan was established after the 1893 Durand Line Agreement between British Mortimer Durand of the British Empire and Amir Abdur Rahman Khan of Afghanistan for fixing the limit of their respective spheres of influence. The single-page agreement, which contains seven short articles, was signed by Durand and Khan, agreeing not to exercise political interference beyond the frontier line between Afghanistan and what was then the British Indian Empire.  The Durand Line was reaffirmed as the International Border between Afghanistan and British Raj in the 1919 Anglo-Afghan War after the Afghan tactical defeat. The Afghans undertook to stop interference on the British side of the line in the subsequent Anglo-Afghan Treaty of 1919 in Rawalpindi.
Pakistan inherited the Durand Line agreement after its independence in 1947, but the Afghan Government has always refused to accept the Durand Line Agreement. Afghanistan has several times tried to seize Pakistan's western provinces of Balochistan and Khyber Pakhtunkhwa. The then Afghan Prime Minister, Muhammad Hashim, said "if an independent Pashtunistan cannot be set up, the frontier province should join Afghanistan. Our neighbor Pakistan will realize that our country, with its population and trade, needs an outlet to the sea, which is very essential", in an interview with the Statesman. In 1949, Pakistan Air Force bombed the Afghan sponsored militant camps in border areas including an Afghan village to curb an unrest led by Ipi Faqir propagating independent Pashtunistan. Border clashes were reported in 1949–50 for the first time. On September 30, 1950, Pakistan claimed that Afghan troops and tribesmen had crossed into Pakistan's Balochistan, but the low-scale invasion was repelled after six days of fighting. The Afghan government denied its involvement and claimed that they were pro-Pashtunistan Pashtun tribesmen.
Tensions soared with the Pakistani One Unit program, and both countries withdrew ambassadors and diplomatic staff in 1955. The Pakistani Embassy in Kabul and consulates in Kandhar and Jalalabad were attacked by mobs. In 1960, major skirmishes broke with the Afghan Forces massing out on the Afghan side of the border with tanks. These skirmishes saw the Pakistan Air Force bombarding Afghan forces. This bombardment led to a brief hiatus in the skirmishes. On 6 September 1961, Kabul formally severed diplomatic relations with Pakistan. In 1950 the House of Commons of the United Kingdom held its view on the Afghan-Pakistan dispute over the Durand Line by stating:
His Majesty's Government in the United Kingdom has seen with regret the disagreements between the Governments of Pakistan and Afghanistan about the status of the territories on the North West Frontier. It is His Majesty's Government's view that Pakistan is in international law the inheritor of the rights and duties of the old Government of India and of his Majesty's Government in the United Kingdom in these territories and that the Durand Line is the international frontier.— Philip Noel-Baker, June 30, 1950
The members of the Council declared that their governments recognised that the sovereignty of Pakistan extends up to the Durand Line, the international boundary between Pakistan and Afghanistan, and it was consequently affirmed that the Treaty area referred to in Articles IV and VIII of the Treaty includes the area up to that Line.— SEATO, March 8, 1956
The Afghan government, having secured a treaty in December 1978 that allowed them to call on Soviet forces, repeatedly requested the introduction of troops in Afghanistan in the spring and summer of 1979. The 1979 Soviet war in Afghanistan forced millions of Afghans to take refuge inside Pakistan. Pakistani officials feared that the Soviet Union began some kind of military show down and that Pakistan or at least its Balochistan province was next on the Soviet agenda. During the early 1980s, multi-national mujahideen forces (consisting of about 100,000 fighters from forty different Muslim countries in addition to 150,000 local fighters) found support from the United States, Saudi Arabia, Pakistan, and Iran in the context of the Cold War. They were trained by Pakistani military in its frontier region around the Durand Line. The Soviet Union decided to withdraw in 1989 and when aid dried up on Afghanistan in 1992, a civil war began. This was followed by the rise and fall of the Taliban government. Since late 2001, as high as 140,000 NATO-led troops were stationed in Afghanistan to train Afghans and rebuild their war-torn country. In the meantime, the Taliban insurgency began around 2004. To counter the insurgency and bring stability in Afghanistan, the United States built bases and garrisons for the Afghan National Security Forces, and is using unmanned aerial vehicles to carry out drone attacks in Pakistan, mainly the Haqqani network in and around the Federally Administered Tribal Areas (FATA).
In September 2017, Brad Sherman, a US lawmaker, suggested conditioning US aid to Afghanistan to the recognition of Durand Line. He added:
I realise that's tough. They'll say, oh, don't — but the fact is, as long as Afghanistan leaves open the idea that they're claiming Pakistani territory, it’s going to be very hard to get the Pakistanis involved, as we need them involved, in controlling the Afghan Taliban.— Brad Sherman, September 7, 2017
Post Taliban rule skirmishes
The following is an incomplete list of recent events relating to the Afghanistan–Pakistan skirmishes. Most of these events cannot be independently verified because news journalists usually have very limited access to reaching the areas where the fighting take place.
- 13 May 2007 – Afghan soldiers attacked Pakistani military outposts which they claimed were illegally built on Afghan soil, one Pakistani soldier was injured. Pakistan's military responded with artillery fire on targets in Afghanistan, reportedly destroying three ANA border posts killing 32 Afghan soldiers. Afghanistan also accused Pakistani military ground contingent crossed the border more than a mile into Afghanistan's Paktia province and killed two Afghan civilians. Gen. Azimi also accused the Pakistani military of using artillery, saying the alleged attack was a clear violation.
- 3 February 2011 – One Pakistani and 7 Afghan soldiers were killed and three others injured after a clash broke out along the border between Pakistani and Afghan forces including an Afghan Colonel. 3 Afghan Soldiers was arrested by Pakistani Forces and later returned. An Afghan commander in Khost confirmed the exchange of fire and alleged that the incident broke out after Pakistani troops in Waziristan opened fire towards Afghan police posts in Gurbuz District, claiming the Afghan engagement as retaliation. However, a military official in Peshawar said Afghan troops fired on an army check post in Ghulam Khan, North Waziristan and that the fire emanated from Afghan territory first. "We are responding with artillery and mortars," he added.
- 28 April 2011 – Border firing broke out in South Waziristan. At least 12 Afghan troops and one soldier from the Pakistan Frontier Corps were killed in the clash, although another source put the Afghan casualties at 8. The attack came just a week after Afghan soldiers had struck in Lower Dir, killing 2 Pakistani security personnel and 40 militants. According to the Pakistani military, Afghan troops opened "unprovoked firing" from across the border and also damaged a market, causing troops from the Pakistani side to respond with fire. However, Afghanistan blamed Pakistan for the clash and denied any Afghan casualties, claiming that only three Pakistani troops were killed. According to Pakistani intelligence analysts, foreign coalition forces have been encouraging Afghan troops to attack border posts. Pakistan also demanded an immediate meeting to discuss the incident.
- June 2011 – Afghanistan blamed Pakistan for killing dozens of Afghan civilians in cross-border shelling conducted for several months. The Afghan government called for the immediate cessation of the artillery fire from Pakistan against Afghan villages. Gen. Zahir Azimi said around 150 missiles fired from Pakistan had landed in different areas of Kunar province.
- July 2011 – Over 150 Afghans in Kabul took to the streets to protest and condemn what they alleged as continuous cross-border shelling and bombardment by Pakistan in Afghanistan's eastern provinces that were said to have killed 12 and left a few wounded. The angry protesters expressed anger over the 470 rockets fired into Afghanistan allegedly from the Pakistani side. Pakistan rejected the Afghan government accusations, saying a "few accidental rounds" may have been fired when it chased unknown militants who had crossed over from Afghanistan and attacked its security installments.
- 19 July 2011 – Pakistan claimed that over 20 mortar shells were fired from Afghanistan which killed 4 Pakistani soldiers and wounded another 2. Pakistan blamed the Afghan National Army for the attack.
- 27 August 2011 – at least 2 Pakistani security personnel were killed and seven others injured in Chitral after militants crossed the border from Nuristan province and initiated firing. The Pakistani government blamed Afghanistan, saying since their expulsion from Pakistani tribal areas, militants were regrouping in Kunar and Nuristan with the support of local Afghan authorities.
- 7 September 2011 – Protesters from Chitral staged a demonstration outside the Peshawar Press Club against an alleged continuous Taliban infiltration into Pakistan from Afghanistan, including the abduction of 30 Pakistani children a week ago on the day of Eid ul-Fitr. The protestors said they would stand against insurgents if their region was attacked in the future and blamed the Afghan government, claiming that Afghan authorities and NATO forces were failing to contain Afghanistan-based militants. The protestors also urged the need to increase the presence of border forces and called on the federal government to take up the issue with the Afghan government to avoid future incidents.
- 25 September 2011 – Afghan authorities claimed that more than 340 rockets had been fired over the course of four days from Pakistani territory. The rockets damaged a few buildings, resulted in the death of a child and also forced hundreds to flee their homes. An employee from the Afghan Ministry of the Interior did not disclose the source of the cross-border shelling but said: "We call on Pakistan, whoever is behind the attacks, to prevent it immediately."
- 10 October 2011 – Pakistani security forces claimed that they killed 30 Afghan militants when a group of 200 insurgents from Afghanistan crossed the border into Pakistan. One Pakistani soldier was also killed in the exchange.
- 12 January 2012 – Pakistani Special Forces Troops from elite Special Services Group entered 4 to 5 km deep inside Afghan borders from Lower Dir area in pursuit of militants. Afghan Forces opened fire in retaliation, 11 Afghan Soldiers were killed in the exchange of fire. Pakistan immediately withdrew without any casualties. Afghanistan also blamed SSG Commandos for taking away the body of a killed Afghan Army Major.
- 8 June 2013 – Pakistan Army Aviation Bell AH-1 Cobra Gunship Helicopters crossed the border from North Waziristan into Paktia and hit 3 TTP Targets before returning.
- 20 December 2014 – JF-17 Thunders from Pakistan Air Force Western Air Command flew into Afghanistan in Kunar Province and reportedly hit 27 targets. Air strikes were carried out in three phases throughout the night and reportedly 50 militants were killed. An Afghan soldier was also killed when an Afghan mobile patrol was mistakenly identified as a militant vehicle by Pakistani aircraft, SSG was also sent in to get the bodies of as many militants as possible. ANA troops did not retaliate against the Pakistani aircraft as the Ministry of Defence (Afghanistan) directed them not to engage Pakistani forces.
- 23 August 2015 – Four Pakistani soldiers manning a border check post were killed in a rocket attack which originated from Afghanistan. This followed an attack on 16 and 17 August in which three Frontier Constabulary officers had also been killed.
- 13 June 2016 – A Pakistan Army Major Ali Jawad Changezi was injured by Afghan firing along Torkham border. Jawad later died in CMH Peshawar on 14 June. Two Pakistani border guards and nine civilians were also injured in Afghan firing. Afghans started "unprovoked firing" at roughly 9pm on Sunday to disrupt the construction of a gate 37 meters inside the Pakistani side of the border. The gate is designed to curb illegal cross-border movement and check the movement of terrorists, and is part of the greater under-construction Pakistan–Afghanistan barrier. The Torkham border crossing was forced to close due to skirmishes. Afghan chief executive Abdullah Abdullah claimed that one of their soldiers was killed and six were wounded. Pakistan reacted by capturing three Afghan border outposts.
- 14 June 2016 – An Afghan soldier and two civilians were killed allegedly in Pakistani firing and 12 soldiers were also injured.
- 15 June 2016 – An Afghan soldier, Khushal Wakilzada was killed and five others were injured in Pakistani firing, whereas the Torkham crossing remained closed. Pakistan reportedly restarted the construction of the border gate. Two Pakistani soldiers were also injured in Afghan firing.
- 17-19 February 2017 – During the past 48 hours, Pakistani army fired scores of missiles on Goshta District and Lal Pur District in eastern Nangarhar province and Sirkanay District of eastern Kunar province. According to reports, Pakistan’s cross-border shelling has left more than 2,000 families homeless.
- 5 May 2017 – The 2017 Afghanistan–Pakistan border skirmish was when a Pakistani census team was attacked by Afghan forces and in return Pakistani forces attacked the Afghan army.
- 15 April 2018 – Cross-border fire between the Pakistani Army and Afghan forces conducting routine "surveillance" in the Kurram Agency, leaves two Pakistani soldiers dead and five others injured.
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