At least 57 terrorists were killed in airstrikes carried out by the Pakistani military in Khyber Agency's Tirah Valley, media reported."The fresh operation was launched after Tuesday's tragic incident, in which at least 145 people mostly school children died," tweeted Director General Inter-Services Public Relations (ISPR), Maj. General Asim Bajwa, Dawn online reported Thursday.In the aftermath of deadly Taliban attack on an army-run school in Peshawar, Pakistan's military launched 20 air strikes.General Bajwa added that the operation was ongoing.