Mirror universe
An F-5 Tiger II fighter
The F-5 Tiger II was a type of military fighter jet aircraft used in the mirror universe on Earth during that planet's 20th century. (ENT: "In a Mirror, Darkly")
Although not mentioned by name, the F-5 Tiger II fighter appeared in the opening credits, indicating the craft was manufactured and used in that universe. Although the exact version of F-5 is not known, the image appears to be of an aggressor aircraft, meaning that it is a Tiger II and not a Freedom Fighter.