Missile Trident 2D5

The Trident II D5 was initiated in the early 1970s as a successor to the Trident C-4 to provide increased accuracy and payload capacity. Formal development was directed in 1981, with land-based test launches conducted between 1987 and 1989. The first submarine-launched test in 1989 failed after a water plume interfered with the motor nozzle, delaying initial operating capability until March 1990. A life-extension version is intended to remain in service through 2042.

The missile is a three-stage system employing solid-fuel rocket motors and NEPE-75 propellant. The hull is constructed from carbon-fiber-reinforced polymer and incorporates 3D printed components. A nose-mounted extendable aerospike is used to reduce drag during the boost phase. Guidance is provided by an astro-inertial system that uses star positioning to update the inertial navigation data during flight. This configuration enables the engagement of hardened targets such as missile silos and bunkers.

United States warhead options include the Mk-5 reentry vehicle with W88 warheads (475 kt) and the Mk-4A reentry vehicle with W76-1 (90 kt) or W76-2 (5–7 kt) warheads. The Mk-4A utilizes the MC4700 arming, fusing, and firing system designed to improve effectiveness against reinforced structures. Future developments include the W93 warhead and the Mk-7 reentry vehicle. United Kingdom variants utilize the Holbrook warhead (100 kt) and the Mk-4A reentry vehicle, with the Astraea warhead planned as a replacement.

The system is operated by the United States Navy and the Royal Navy. It is carried by Ohio-class and Vanguard-class submarines and is designated for use on future Columbia-class and Dreadnought-class platforms. The United Kingdom draws its inventory from a shared pool maintained with the United States Navy at Kings Bay, Georgia. Of 215 total test launches, 207 have been successful. Recorded flight failures include the initial 1989 sea trial and a 2024 test conducted by a Royal Navy submarine off the coast of Florida.