The terror group suspected of carrying out Thursday's bomb attack at Kabul airport took root in eastern Afghanistan in 2015.
Prior to the attack fears had been expressed that Islamic State-Khorasan Province, also known as Isis-K would strike Taliban fighters guarding the area, US troops mounting the evacuation operation and the throng of Afghans and foreigners who had massed at airport gates.
Commenting on Tuesday on his decision to pull all US troops out of Kabul by August 31st, US president Joe Biden said: "Every day we're on the ground is another day we know that Isis-K is seeking to target the airport and attack both US and allied forces and innocent civilians."
While another terror group, al-Qaeda, has co-operated with the Taliban in its takeover of the country, Isis-K has clashed with US and Taliban forces and staged attacks on civilians in Kabul and elsewhere, repeatedly targeting ethnic Shia Hazaras.
The Sunni extremist group's most notorious operations took place in May 2020, when it attacked a Médecins Sans Frontières maternity clinic in Kabul, killing 24 mothers and babies and a staff member, and in May this year,when an Isis-K suicide truck bomber struck a girls' school in Kabul, killing 68 and wounding 165.
The group became established in eastern Afghanistan six years ago when the US was leading an offensive against the cross-border caliphate established in Syria and Iraq by its parent movement, Islamic State, also known as Isis.
According to the Washington-based Center for Strategic and International Studies, Isis-K was founded by Pakistani Hafiz Zaeed Khan, who had pledged fealty to Islamic State head Abu Bakr al-Baghdadi. The original group was made up of mainly Pakistani Taliban defectors and members of other radical factions who believed the Taliban had deviated from Islamic principles and practices.
In 2017, convinced that Isis-K posed a serious danger to its forces in Afghanistan, the Pentagon dropped the largest conventional bomb in its arsenal on the group’s mountain stronghold, killing some 96 fighters.
The UN has estimated Isis-K could have as many as 1,500-2,200 core fighters or as few as 500, and reported 77 Isis-K attacks between January and April of this year.
Recent operations have been carried out by sleeper cells based in or near cities as the Taliban have denied the movement a substantial territorial base.
Nevertheless, an unnamed humanitarian official told the broadcaster Voice of America that the group was “building local infrastructure for recruitment, logistics [and] economic support”.
A Pentagon report issued in April said the expansion of Isis-K was a “top concern” for Afghanistan’s neighbours.
Islamic State was the sole jihadist group to condemn the US withdrawal deal with the Taliban, accused the Taliban of abandoning the jihadist cause and vowed to carry on the fight.