The Boeing F-15EX Eagle II is an American all-weather multirole strike fighter derived from the McDonnell Douglas F-15E Strike Eagle.[1] The aircraft resulted from the U.S. Department of Defense' Cost Assessment and Program Evaluation (OSD CAPE) study in 2018 to recapitalize the aging F-15C/D fleet due to inadequate numbers of F-22s, delays in the F-35 program, and maintaining diversity in the U.S. fighter industrial base through Boeing's St. Louis division (former McDonnell Douglas). The F-15EX is expected to replace the F-15C/D in performing homeland and air defense missions and also serve as an affordable platform for employing large stand-off weapons to augment the frontline F-22 and F-35. The first aircraft was delivered in 2021 and operational service is expected in July 2024.