A defense perimeter was an assortment of military units before or around a specific location, designated to defend this location against attacks. This could take place in space or on a planetary surface.

By 2152, Ty'Gokor was protected by a defense perimeter. After his demotion, Duras was posted there as a second weapons officer. (ENT: "Judgment")

In an alternate timeline's 2153, the Enterprise was boarded by a group of Xindi-Reptilians. T'Pol ordered Malcolm Reed to have his men set up a defense perimeter on B deck. (ENT: "Twilight")

Later in 2153, Degra claimed the Enterprise would never reach the Xindi weapon as the Xindi defense perimeter would destroy them before reaching Azati Prime. (ENT: "Stratagem")

By 2366, the inner planets of the Sol system were defended by the Mars Defense Perimeter. (TNG: "The Best of Both Worlds, Part II")

In 2371, Banea was protected by a defense perimeter from Numiri attacks. (VOY: "Ex Post Facto")

In 2373, Starfleet established a defense perimeter in the Typhon sector against a Borg cube en route to Earth, but the cube broke through the perimeter. (Star Trek: First Contact)

That year, when the USS Voyager had been invaded by a macrovirus, Neelix speculated the ship's crew was hiding from it and had set up a defense perimeter. (VOY: "Macrocosm")

In 2374, a group of Jem'Hadar established a defense perimeter around a cavern they had set-up camp in after crash landing on a planet. (DS9: "Rocks and Shoals")

The same year, Nog suggested setting up a defense perimeter around the infirmary of Empok Nor, when he and other Ferengi had established their base there. (DS9: "The Magnificent Ferengi")

Again in 2374, General Martok sent three Klingon attack cruisers to bolster the defense perimeter of the Dorala system. (DS9: "The Reckoning")

By 2374, Starbase 257 maintained a defense perimeter, which leaving or incoming vessels needed clearance to pass through. Vessels were supposed to stay at half impulse within the perimeter. (DS9: "Valiant")

In 2375, Captain Benjamin Sisko told Lieutenant Larkin, she had set up a solid defense perimeter around the communication array on AR-558, but needed to tighten up a flank. (DS9: "The Siege of AR-558")

Later that year, the Kelvas facility also maintained a defense perimeter. (DS9: "Tacking Into the Wind").

In late 2375, the Dominion established a defense perimeter around Cardassia Prime. In orbit, Damar's attack ship was destroyed by a Breen ship, part of the defense perimeter. After the Dominion's final retreat towards Cardassia Prime, the defense perimeter was composed of thousands of Jem'Hadar and Breen ships as well as Cardassian orbital weapon platforms. (DS9: "The Dogs of War", "What You Leave Behind")

By 2377, the Kraylor homeworld was protected by a defense perimeter. (VOY: "Nightingale")

See Also

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