Updated

The leader of the Islamic State (ISIS) terror group in Afghanistan and Pakistan was killed by a U.S. drone last month, a U.S. defense official confirmed to Fox News Friday.

Pentagon spokesman Gordon Trowbridge said that Hafiz Saeed Khan died July 26 from an airstrike in Nangarhar province in eastern Afghanistan.

"Khan was known to directly participate in attacks against U.S. and coalition forces, and the actions of his network terrorized Afghans, especially in Nangarhar," Trowbridge said. 

The spokesman added that ISIS had been active in the region since last summer and used the area to train and equip militants and provide a "continuous supply of enemy fighters."

The State Department last year designated Khan a global terrorist, saying he is the leader of the Islamic State in Khorasan, which includes former members of the Pakistani and Afghan Taliban. Khan had previously been a Tehrik-e Taliban commander, but last year pledged loyalty to ISIS leader Abu Bakr al-Baghdadi.

Khan was reported killed last year but the death was never confirmed.

U.S. and Afghan leaders have been concerned about the growth of ISIS in Afghanistan. They were targeted by a U.S.-backed Afghan military offensive last month, in which five U.S. commandos were injured.

In January, President Obama authorized U.S. airstrikes against ISIS in Afghanistan. Officials believe there are between 1,000-1,500 ISIS in eastern Afghanistan.

Khan is the second prominent jihadist to be killed in the region in three months. Afghan Taliban leader Mullah Akhtar Mansour was killed by a US airstrike strike in Pakistan in May.

Fox News' Lucas Tomlinson and the Associated Press contributed to this report.

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