The Lockheed Martin Lightning II fighter jet is the world’s most advanced fighter and is taking its place as the second-most in-service fighter jet in the world (depending on how the numbers are counted). At the same time, the Air Force is planning to double the number of F-15EXs it is procuring to 267. Importantly, this is not so much increasing its F-15 fleet as it is intended to recapitalize the aging F-15E fleet as they age out and retire.