At least 21 suspected terrorists were killed on Friday in military air strikes in Pakistan's Khyber Agency, said security sources.Pakistan Air Force jets targeted militant hideouts in Tirah Valley, killing at least 21 suspected terrorists and razing several hideouts, Dawn reported.Khyber Agency is one of seven semi-autonomous tribal districts where government forces have traditionally had little control and militant groups thrive.The Pakistan Army launched Operation Zarb-i-Azb, a grand operation in the North Waziristan tribal region, following a Taliban attack on the Jinnah International Airport in Karachi in June 2014.