Islamic State has claimed responsibility and experts say an IS branch – Islamic State Khorasan Province – is prime suspect

Islamic State (IS) has claimed responsibility for the attack, praising the “Islamic fighters” who carried it out. Many commentators and US officials have pointed to the IS affiliate called Islamic State Khorasan Province (ISKP) as prime suspect – though so far there is no evidence that this is the case.

ISKP is a branch of Islamic State in Afghanistan. The name comes from that given to a region by some local Islamic rulers and so explicitly rejects modern national frontiers while evoking what its members consider the lost glory and power of Muslim empires.

It was formed at the peak of the expansion of IS in 2015 when the Iraq- and Syria-based group was trying to expand by building a network of affiliates through the Middle East, the Maghreb, west Asia and other parts of Africa. These efforts brought mixed results. However, hundreds of disillusioned Taliban fighters and some from factions in Pakistan were attracted by the extremism and resources of IS. These formed the nucleus of ISKP – and the group remains linked to IS to this day.