Born out of Afghan War (1979-89) the HuJI is an Islamist-jihadist organization operating in Pakistan. Its exact year of coming into being is not known but considered to be 1983, when it started jihadi activities in Afghanistan alongside Afghan Islamist groups. According to Federation of American Scientists (FAS) note on HuJI,"HUJI, a Sunni extremist group that follows the Deobandi tradition of Islam, was founded in 1980s in Afghanistan to fight in the jihad against the Soviets. It also is affiliated with the Jamiat Ulema-i-Islam Fazlur Rehman Jalili faction (JUI-F) and the Deobandi school of Sunni Islam. The group, led by Qari Saifullah Akhtar and chief commander Amin Rabbani, is made up primarily of Pakistanis and foreign Islamists who are fighting for the liberation of Jammu and Kashmir and its accession to Pakistan." 
The US State department's annual Country Report on Terrorism, 2010, describes HuJI as, "HUJI was founded in 1980 in Afghanistan to fight against the Soviet Union. Following the Soviet withdrawal from Afghanistan in 1989, the organization re-focused its efforts on India. HUJI seeks the annexation of Indian Kashmir and expulsion of Coalition Forces from Afghanistan. In addition, some factions of HUJI espouse a more global agenda and conduct attacks in Pakistan as well. HUJI is composed of militant Pakistanis and veterans of the Soviet-Afghan war. It has also supplied fighters for the Taliban in Afghanistan. HUJI has experienced a number of internal splits and a portion of the group has aligned with al-Qa'ida (AQ) in recent years, including training its members in AQ training camps." 
HuJI was in fact the first Islamist armed non-state actor founded in Pakistan during Afghan War. HuJI changed its jihadist front from Afghanistan to Kashmir in 1989. It had become international with opening up of branches in India, Myanmar and Bangladesh.
HuJI's adheres to Deobandi radical school of thought and since its inception it has successfully drawn recruits from Deobandi-madressahs managed by Islamist political party Jamiat-e-Ulema Islam (JUI). It is multi-ethnic in a sense that many of its followers are both Punjabis and Pashtuns. That makes it unique amongst other major radical Islamist violent non-state actors. Zahid Hussain, a well-known Pakistani journalist and an expert on Islamist extremist groups categorized HuJI formation as an act of Pakistani intelligence apparatus to use Islamist militants for their proxy war with India in Kashmir. He described this policy was like ‘playing with fire'.
HuJI has played a key role in providing militant leadership to latter generations of radical Islamist groups belonging to same radical school of thought. The leadership of most of the radical Islamists terrorist organizations in Pakistan was previously part of HuJI. The radical mindset, ideology, training camps, tactics, guerrilla war experience, jihadi spirit, madressah recruitment; leaders from both Punjabis and Pashtun ethnic groups, pan-Islamist radical agendas etc are all today's critical issues that in fact sprang out of the fountainhead of HuJI.
HuJI was founded by Maulana Irshad Ahmad and his trusted lieutenants Qari Saifullah Akhter and Fazal ur Rehman Khalil. Irshad Ahmad was a Punjabi, whereas Akhter and Khalil were Pashtuns, hailing from Khyber-Pakhtunkhawa province of Pakistan. All of them had graduated from Deobandi seminary Jamia Uloom-e-Islamia Banori Town in Karachi.
HuJI initially drew its support base and inspiration from Harkat-e-Inquilab e Islamic (Movement for Islamic Revolution), one of the Afghan Islamist/jihadist party, and also one of Peshawar Seven parties. According to Mohammad Amir Rana, a leading expert on Pakistani jihadi organizations, "Maulana Irshad Ahmed created Harkatul Jehadul Islami in 1979. When the Soviet troops entered Afghanistan Maulana Irshad Ahmed led the first delegation of religious scholars from NWFP (now KP-province) to that country to participate in the war... Harkatul Jehad made contact with Maulana Mohammad Nabi Mohammadi's organization Harkatul Inqalab Islami during the Afghan War. This was an organization that held Deobandi views."
After the death of Irshad Ahmed while fighting the Soviets in Afghanistan's Kunar province in 1985, Akhter took over HuJI. Akhter turned the organization's structure and made it international within years. Fazal ur Rehman Khalil later parted ways and founded another jihadi organization called Harkat-ul-Mujahedeen (HuM). Khalil was the one present with Bin Laden in 1998 when Laden proclaimed his Fatwa against the west and America. He was also one of the signatories. Another prominent figure Masood Azhar founded Jaish-e-Mohammad (JeM), after getting released from Indian prison as a result of hijacking of an Indian airliner in 1999. 
HuJI is simultaneously Afghan jihadist, Kashmiri, sectarian, pro-Taliban, Al-Qaeda-linked, and anti-western and anti-American. Thus, implying the point made earlier about the diverse characteristics of such kind of Islamist-deobandist-wahabist violent non-state actors.
HuJI remained active against Soviets and then Indians but it was during Prime Minister Benazir Bhutto second tenure in 1995 that it showed its true ambitions. And it was from then onwards that HuJI and its leader Qari Saifullah Akhter became known to Pakistani masses.
In 1995, HuJI leader Saifullah Akhter in collusion with Pakistan Army's Islamist generals Zaheer ul Islam Abbasi and Mostansir Billah, attempted to topple the Bhutto government in a coup d'Etat. The plan was to eliminate the entire top brass of civil and military establishment and replace it with caliphate. That was the reason that the plan was called ‘Operation Caliphate'. According to Khaled Ahmed, "the leader of HuJI, Qari Saifullah Akhter first came to public view when he was caught in the 1995 unsuccessful coup led by Major General Zaheer ul Islam Abbasi, but saved his skin by turning state witness. (Some say he was defiant but was still let off). After that he surfaced in Kandahar, and from 1996, was an advisor to Mullah Umar in the Taliban government. His fighters were called ‘Punjabi Taliban'." 
Benazir Bhutto later named rogue Islamist elements within the military for planning and targeting her time and again. She in her autobiography, mentioned Lt General (retired) Hamid Gul (former DG of ISI) of hiring Akhter and his jihadist group to assassinate her. She accused Akhter and HuJI for attempting to launch a coup in 1995, then an attempted suicide attack against her procession in October 2007 and warned of further plans of eliminating her from the scene. 
Amir Rana also highlighted the role of HuJI in bringing about violent Islamic revolution in Pakistan in his book on Pakistani radical Islamist jihadist groups, "Harkatul Jehadul Islami has tried many times to bring about a revolution in Pakistan. In 1995, when Major General Zahirul Islam Abbasi and Brigadier Munstansir Billah planned a mutiny against GHQ (General Headquarters of Pakistan Army located in Rawalpindi, 20 kilometers from capital Islamabad) Qari Saifullah Akhter, the amir of HuJI (then part of Harkatul Ansar), was part of the plan and was supposed to help with manpower and funds." 
During 1990s, HuJI played a key role in Indian Kashmir insurgency. Other organizations of same school of thought (offshoots such as Brigade-313, Al-Madina, Al-Faran) were also active in exerting their influence in Indian Kashmir. It was then a rapprochement was reached between HuM and HuJI in order to share resources and perform better in an environment becoming highly competitive. The two organizations, with some other minor factions got merged and took a new name, Harkatul Ansar, in 1993. But the alliance did not last for very long and parted ways.
Because of its traits and history HuJI eventually became part of pro-Taliban alliance of radical Islamist VNSAs after 2001 US invasion of Afghanistan. Amir Mir described this alliance as Brigade 313. Although Akhter is out of scene but the organization has become more lethal and every major terrorist attack in Pakistan has led investigators to HuJI or its offshoots' involvement. The alliance is now being led by one HuJI stalwart Ilyas Kashmiri (there have been unconfirmed reports of his death in a drone attack in South Waziristan, June, 2011).
According to Amir Mir, "Harkat and Jaish were components of a five member ‘Brigade 313', which was launched in 2001 after the fall of the Taliban regime in Afghanistan. Three other components of the Brigade 313 were Lashkar-e-Jhangvi (LeJ), Jaish-e-Mohammad (JeM), and Lashkar-e-Taiba (LeT)."
Khaled Ahmed describes HuJI as the most dangerous Islamist jihadi organization in Pakistan as it traces being found in every major conspiracy and attacks. It is the lynchpin of jihadist tendencies with links starting from Pakistani Islamist radical groups to Taliban and Al-Qaeda. For HuJI's profound links to Taliban regime, he said, "Three Taliban ministers and 22 judges belonged to the Harkat. In difficult times, the Harkat fighters stood together with Mulla Umar. Approximately 300 of them were killed fighting the Northern Alliance, after which Mulla Umar was pleased to give Harkat the permission to build six more maskars in Kandahar, Kabul and Khost, where the Taliban army and police also received military training. From its base in Afghanistan, Harkat launched its campaigns inside Uzbekistan, Tajikistan and Chechnya."
About HuJI's international links with other Islamist groups and its militant activities in Kashmir he further elaborated, "To date, 650 Harkat al-Jahad al-Islami mujahideen have killed in battle against the Indian army: 190 belonging to both sides of Kashmir, nearly 200 belonging to Punjab, 49 to Sindh, 29 to Balochistan, 70 to Afghanistan, 5 to Turkey, and 49 collectively to Uzbekistan, Bangladesh and the Arab world." [i] 
Hundreds of HuJI activists lost their lives while fighting against Northern Alliance during Taliban regime, clearly stating its affiliation with Al-Qaeda. It was Al-Qaeda during 1996-2001 periods that provided a separate battalion of non-Afghans under ‘Brigade-055' that fought alongside Taliban forces at northern fronts.
HuJI could be categorized as ‘militant religious movement' under the model provided by Thomas, Casebeer and Kiser. Considering the level of activities and strength it is well groomed and experienced. Since after 9/11 attacks it has turned against the Pakistani state and has been able to foster its relations with other Islamist violent non-state actors, both domestic and foreign. Most of HuJI is what now, is part of Tehreek-e-Taliban's (TTP) Punjabi Taliban wing.
Apart from breaking down into core militant groups like HuM and JeM, the old veteran organization also gave birth to several splinter groups, currently active in hundreds of attacks against both civilian and military targets in Pakistan. Some of those groups were identified as:
HuJI's Splinter Factions
HuJI has a long and enduring relationship with Al-Qaeda Cenrtal, based in tribal areas of Pakistan and the relationship predates Global War on Terror. HuJI leaders were given high profile position by Taliban supreme commander Mullah Omar and in response the HuJI played a pivotal role in cementing strategic ties between the Taliban and Al-Qaeda. With the commencement of GWOT, HuJI could be best described as the Islamist violent non-state actor well-integrated into Al-Qaeda Central. HuJI's offshoot Brigade-313 led by former HuJI commander Ilyas Kashmiri is now considered the most lethal and active Al-Qaeda strike force in Pakistan. It has been involved in numerous incidents of terrorism. Other HuJI offshoots (see diagram) have also been involved in creating havoc on mainland Pakistan. HuJI core has been able to conduct 19 terrorist attacks since 2001 in Pakistan in collusion with Al-Qaeda Central based in Pakistan's tribal areas.