An attack on the Iraqi embassy in Kabul has reinforced fears that Islamic State militants are seeking to bring the group's Middle East conflict to Afghanistan, though evidence of fighters relocating from Iraq and Syria remains elusive.
Islamic State said it carried out Monday's attack, which began with a suicide bomber blowing himself up at the embassy's main gate, allowing gunmen to enter the building and battle security forces.
The choice of target, three weeks after the fall of Mosul to Iraqi troops, appeared to back up repeated warnings from Afghan security officials that, as IS fighters were pushed out of Syria and Iraq, they risked showing up in Afghanistan.
"This year we're seeing more new weapons in the hands of the insurgents and an increase in numbers of foreign fighters," said Afghan Defence Ministry spokesman Gen Dawlat Waziri. "They are used in front lines because they are war veterans."
One senior security official put the number of foreigners fighting for both IS and the Taliban in Afghanistan at roughly 7,000, most operating across the border from their home countries of Pakistan, Uzbekistan or Tajikistan, but also including others from countries such as India.
'New tactics, weapons'
US commanders say that, in partnership with Afghan security forces, they have severely reduced IS's strength over the past year with a combination of drone strikes and Special Forces operations.
But according to Afghan intelligence documents, security officials believe IS is present in nine provinces, from Nangarhar and Kunar in the east to Jawzjan, Faryab and Badakhshan in the north and Ghor in the central west.
Afghan officials say newly arrived foreign fighters have been heavily involved in fighting in Nangarhar province, IS's main stronghold in Afghanistan, where they have repeatedly clashed with the Taliban.
"We have our brothers in hundreds from different countries," said an Islamic State commander in Achin district of Nangarhar.
"Most of them have families and homes that were destroyed by the atrocity and brutality of the infidel forces in Arab countries, especially by the Americans," he said. "They can greatly help us in terms of teaching our fighters new tactics, with weapons and other resources."
