The group consists of factions from the Afghan Taliban, the Pakistani Taliban, and remnants of al-Qaeda.
Since its inception, ISKP has targeted Afghan government forces, international coalition forces, and Taliban insurgents. ISKP's attacks in Afghanistan caused outrage.
In 2018, it bombed an office of Save the Children, a charity. In 2019, it bombed a wedding, killing 92 and injuring 140. In 2020, it bombed a maternity hospital, killing newborn babies, mothers, and nurses.
US and former Afghan government forces went after ISKP militants in eastern Afghanistan and killed several senior figures from the group.
Afghan forces captured its leader, Aslam Farooqi, along with several other senior commanders, including Qari Zahid and Saifullah (aka Abu Talha) in Kandahar province in March 2020.
At the same time, Iran worked with the Taliban to fortify the Iran-Afghan border to curb the movement of ISKP fighters.
Exploiting discontent
ISKP is against any form of compromise with the West. This resonated with disillusioned former Taliban members who opposed the Taliban's negotiations with the US prior to the latter's withdrawal from Afghanistan in August 2022.
American and Afghan soldiers at the US withdrawal ceremony in 2021.
As a result, ISKP said the Taliban was "collaborating with crusaders" and vowed retribution. It adheres to Tawhid Al-Hakimiyyah, or the sovereignty for Allah alone, so it does not acknowledge the legitimacy of the Taliban as rulers.
ISKP portrays the Taliban as a nationalist faction with parochial ambitions focused on establishing an Afghan state, as opposed to its own goals, such as global jihad.
According to a 2018 report by the Washington-based Centre for Strategic and International Studies, ISKP has had support from the core IS leadership in Iraq and Syria since it was set up in 2015.
Following the loss of IS territory, ISKP shifted its international efforts towards Afghanistan, aiming to establish it as a focal point for its purported global 'caliphate.'
When it pledged allegiance to the global caliphate envisioned by IS, others in Iraq and Syria with the same affiliation applauded the expansion of influence in Central Asia.
To bolster its networks there, IS allocated money to the Khorasan region.
Meanwhile, the United Nations said IS "continues to facilitate the relocation of some of its key operatives to Afghanistan". These included Abu Qutaiba, the former leader of IS in Salahuddin province, Iraq.
Foreign fighters were drawn to ISKP in Afghanistan in part because it was adept at managing its operations and promoting itself among Muslims. Often, fighters would choose to join ISKP over other more local units.
The US views the group as a serious threat. Since designating it a terrorist organisation in January 2016, US Central Command (CentCom) has launched an aerial offensive against ISKP, which has only expanded.
Between January 2017 and October 2018, the US and NATO conducted more than 300 airstrikes against ISKP, according to the Armed Conflict Location and Event Data Project (ACLED).
Most of these (96%) were conducted in Nangarhar and Kunar provinces, which lie between Kabul and the Pakistani border, where ISKP leaders and bases are sited.
Kabul bombing
In August 2021, the group made global headlines by bombing Kabul Airport, killing more than 170 people, including 28 Taliban fighters and 13 US soldiers.
It was interpreted as a message from ISKP to their Taliban rivals, who had not yet solidified control over Afghanistan. Key facilities remained vulnerable to IS attacks.
The site of the August 26 double suicide bombing at Kabul Airport on August 27, 2021.
ISKP forces based themselves in Nangarhar province so they could benefit from drug smuggling and human trafficking routes into Pakistan. This led to tension and irritation for the Taliban government, Islamabad, and Washington.
After the airport bombing, ABC News interviewed Colin Clarke, a counterterrorism expert, who said ISKP followed a decentralised structure along the model run by al-Qaeda to help evade US forces.
Clarke, a senior research fellow and director of policy at the Soufan Centre, estimated that ISKP had up to 2,200 fighters from Arab countries, the Middle East, Pakistan, and South Asia.
He said one of the main differences between it and the Taliban is that ISKP is a transnational organisation aiming to "remain and expand", while the Taliban is a homogenous group of Pashtuns.