Islamabad: The US has confirmed the killing of the mastermind behind the December 2014 carnage at Peshawar's Army Public School in a drone strike in Afghanistan, Pakistani officials said. A statement issued by the Inter-Services Public Relations said that the US Commander of the Resolute Support Mission General John Nicholson called Chief of Army Staff General Raheel Sharif on Wednesday and confirmed the death of terrorist Umar Mansour in Afghanistan. According to Pakistan security officials, he was killed on July 9 in a US drone attack in the Bandar area of Afghanistan’s Nangarhar province, Dawn online reported. Mansour masterminded the December 16, 2014, attack on the Army Public School in Peshawar which killed 122 students and 22 teachers. Mansour belonged to Tehreek-i-Taliban Pakistan's (TTP) Tariq Geedar group and used to operate in Peshawar and adjoining Frontier Region Peshawar and Darra Adamkhel. Mansour fled to Afghanistan following a military operation in Khyber tribal region and continued to operate from there. He was held responsible for the September 2015 attack on a Pakistan Air Force base in Peshawar’s Badaber area, which killed 29 people. He was also behind the January 2016 attack on the Bacha Khan University in Charsadda in which 18 students and faculty members lost their lives. He was not considered as a threat to the US until it declared him a ‘global terrorist’ on May 25 - four days after the US targeted Afghan Taliban chief Mullah Akhtar Mansour in a drone strike in Balochistan.