For nearly three decades, the F-15 Eagle fighter was considered the undisputed king of the skies. Until the debut of its replacement, the F-22 Raptor, the F-15 was the U.S. Air Force’s frontline air superiority fighter. Even today, a modernized Eagle is still considered a formidable opponent, and manufacturer Boeing has proposed updated versions that could keep the airframe flying for the better part of a century. The F-15 traces its roots to the air war in Vietnam, and the inauspicious showing of American Air Force and Navy fighters versus their North Korean counterparts. Large, powerful American fighters, designed to tackle both air-to-air and air-to-ground missions, were performing poorly against their smaller, less powerful—but more maneuverable—North Vietnamese counterparts.
http://nationalinterest.org/feature/why-americas-enemies-still-fear-the-f-15-eagle-16897