KABUL—The U.S. Air Force dramatically increased the number of airstrikes it carried out in Afghanistan in 2016, data released by the military shows, a further sign of growing U.S. involvement in the war following the withdrawal of most coalition troops two years ago.

The increased engagement follows the U.S.’s decision last year to widen the military’s authority to conduct offensive operations in Afghanistan amid gains made by the Taliban, its largest insurgency, and Islamic State’s affiliate in the country.

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