(U.S. Air Force A-10 Thunderbolt jets, also known as the Warthog. File photo)

(U.S. Air Force A-10 Thunderbolt jets, also known as the Warthog. File photo)

Pakistani army chief of staff General Ashfaq Parvez Kayani offered a rare apology at the weekend for a deadly air strike in the Khyber region in the northwest  in which residents and local officials say at least 63 civilians were killed.