In this photo released by the U.S. Air Force on May 2, 2023, airmen look at a GBU-57, or the Massive Ordnance Penetrator bomb, at Whiteman Air Base in Missouri. That U.S. bomb, designed to destroy underground sites at the height of concerns a decade ago over Iran's nuclear program, has briefly reappeared amid new tensions with the Islamic Republic. (U.S. Air Force via AP)