Countermeasures of the UNSC Navy

AN/SLQ-371 Universal Decoy and Countermeasure Launcher
The primary component of any warship's active defense systems, the Mark 371 is a turreted, hepta-barreled launch system able to deploy a wide range of munitions deployed from a standardised canister. Available munitions include, but are not limited to: ferric-carbon nanotube chaff, semi-guided multispectrum flares, smoke canisters, electromagnets. The Mark 371 was widely used on all ships during the HCW, but after the war, they were replaced by the larger, more capable M492 Cyclone.

AN/SLQ-419 Deployable Emergency Barrier
These were essentially self-propelled plates of grapheel that are launched in the way of plasma torpedoes and missiles. Rarely used due to their size and mass, but they were one of the surest ways to stop these weapons. These were replaced after the Human-Covenant War by the AN/SLQ-61 Emergency Remote Projected Barriers, which traded the armour for sacrificial shield emitters.

M29A2 Mini-Missiles
Small and fast, the M29A2 micro-missiles were specifically designed to defeat enemy missiles, but their payload was sufficiently strong enough to throw off incoming coilgun slugs as well. Mounted in cells of 15 missiles each, with a variant released with magnetized chaff to disrupt plasma weaponry.

AN/SLQ-83(V) Magnetic Shield
This clever system used the power of a ship's MAC to shape a magnetic field in the direction of incoming projectiles, containing plasma-based weaponry. Available in both directed and encompassing designs, although the directed ones were more effective. Because of their power demands, a given warship could not operate the AN/SLQ-83(V) and charge its MAC at the same time, forcing the captain to choose between firepower or durability.

Mark 28 Laser
Longest-ranged point defense system in service. A directed infrared beam prematurely detonates missiles, and a smaller beam transmits a wide range of early detonation signals to a target. Works best with M29A2 mini-missiles and point defence guns to create a full active protection network around the mothership.

M97 Fire Support Shell
Fired from naval coilguns, the M97 is used to embed itself into the hull of an enemy ship, giving the UNSC the ability to track and fire upon stealth vessels.

AN/SLQ-83 Veil and AN/SLQ-90 Loki Combat Disruption Suites
Designed as an integration electronic warfare array, complete with missile guidance suppression, sensor distortion, and communications jamming. The Loki system introduced during the Human-Covenant War also introduced a sub-slipspace dampening array and a dedicated AI component to enhance effectiveness against the Covenant. The Veil, although good against human vessels, proved hopeless against the Covenant.

AN/SLQ-657(P) Magician Naval Hologram
Based on captured Covenant examples. The Magician had two major variants; a version that was mounted on starships used to obscure hull damage, and a drone-mounted version which projected a complete recreation of the mothership around an M417 Pigeon Electronic Surveillance Drone