Multiple realities(covers information from several alternate timelines)
The F-15 Eagle was a type of military fighter jetcraft.
This type of aircraft was used in the mirror universe on Earth during the 20th century. (ENT: "In a Mirror, Darkly")
Although not mentioned by name, the F-15 Eagle fighter (pictured, right) appeared in the opening credits, indicating the craft was manufactured and used in that universe.
In 2255 of an alternate timeline, the Shipyard Bar in Iowa displayed a model of an F-15 fighter, among others. (Star Trek)