The Eagle has been exported to Israel, Japan, and Saudi Arabia. The F-15 was originally envisioned as a pure air-superiority aircraft. Its design included a secondary ground-attack capability[5] that was largely unused. The aircraft design proved flexible enough that an all-weather strike derivative, the F-15E Strike Eagle, an improved and enhanced version which was later developed, entered service in 1989 and has been exported to several nations. As of 2017, the aircraft is being produced in different variants.