The U.S. Air Force is among an elite club of air forces that has access to fifth-generation fighter jets The F-22 Raptor and F-35 Lightning II are some of the most advanced fighter jets in the American fleet.

U.S. Air Force pilots graduating from training courses with the T-38 Talon may be required to fly non-fighter or bomber aircraft as a result of pilot shortages, according to a new Air Force policy. The challenges in pilot inventory were outlined in an August service memo reviewed by Defense News and confirmed by an Air Force official.

As a program, Lockheed Martin’s F-35 Joint Strike Fighter – aka the Lightning II – has survived a lot of turbulence in the roughly 30 years since the Pentagon first conceived of a do-it-all stealth fighter.