Three attack ships of the Mars Defense Perimeter in 2367
The Mars Defense Perimeter was a Starfleet defense mechanism, designed to protect the inner planets of the Sol system, and specifically Earth, from intruding hostile vessels. Part of the defense perimeter was a series of attack ships.
In early 2367, an attacking Borg cube crossed the perimeter and was able to easily break through the defensive lines. (TNG: "The Best of Both Worlds, Part II")
In 2368 a Mars Defense Perimeter ship was stored in the ship grave yard of Surplus Depot Z15. (TNG: "Unification I")
- The Mars defense vessels were constructed from models of Typhoon- and Los Angeles-class submarines.
- It would appear that a global dust storm was envelopiing Mars during the Defense Perimeter-scene.