Hafiz Sayed Khan, ISIS's top leader in Afghanistan, was killed in a U.S. drone strike on July 26 in eastern Afghanistan, according to a U.S. defense official.
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Khan has been reported as having been killed before, but the official said there has been confirmation that Khan was killed in the airstrike that occurred in Nangarhar Province more than two weeks ago.
"U.S. forces conducted an airstrike targeting Hafiz Sayed Khan, the Islamic State in the Levant-Khorasan emir, in Achin district, Nangarhar province July 26, resulting in his death," said Gordon Trowbridge, deputy Pentagon press secretary, in a statement confirming his death.
According to Trowbridge the airstrike was part of a month-long operation against ISIS carried out by U.S. and Afghan special operations forces this past July in southern Nangarhar province.
Khan was known as the Emir of ISIS-Khorasan, the name of the ISIS affiliate in Afghanistan that has operated mainly in remote areas of eastern Afghanistan along the border with Pakistan.
He was known "to directly participate in attacks against U.S. and coalition forces, and the actions of his network terrorized Afghans, especially in Nangarhar," said Trowbridge.
The number of fighters belonging to the group and the amount of territory held by the group has been reduced by recent Afghan military operations supported by U.S. airstrikes.
Last December, the White House approved an expansion of authorities for the U.S. military in Afghanistan, enabling it to conduct airstrikes against ISIS-Khorasan, which posed a growing threat in eastern Afghanistan.
The Pentagon's latest estimate is that there are now 1,000 to 1,500 ISIS fighters in eastern Afghanistan, nearly half the number estimated earlier this year. Most of these ISIS fighters were members of the Pakistani Taliban that rebranded themselves as ISIS.
"We think we've reduced their numbers fairly significantly in the last six months," Gen. John Nicholson, the top U.S. military commander in Afghanistan, told Pentagon reporters in a video briefing two weeks ago.
"Khan's death affects ISIL-K recruiting efforts and will disrupt ISIL-K's operations in Afghanistan and the region," said Trowbridge.