The Trident II's increased payload allows nuclear deterrence to be accomplished with fewer submarines,[14] and its high accuracy—approaching that of land-based missiles—enables it to be used as a first strike weapon.

[23] The D5 is the sixth in a series of missile generations deployed since the sea-based deterrent program began 60 years ago.

The U.S. Navy conducted studies to determine whether the more expensive Trident II could be constructed similarly to the US Air Force's MX ICBM, primarily to decrease budget costs.

It was established that the Trident II would be 83 inches (210 cm) in diameter and 44 feet (13 m) in length in order to match the performance of the existing MX ICBM.

By December 1978, the Navy's and the Air Force's own studies agreed with each other that a similar missile structure would not achieve desired savings.

[25] The Defense Department directed the Navy to fund all development of the Trident II D5 missile with a December 1989 IOC.

In December 1982, Deputy SECDEF Frank Carlucci advised the Secretary of Defense Caspar Weinberger to include funding for a new reentry vehicle–warhead combination for Trident II.

On 28 December 1983, the deputy SECDEF authorized the Navy to proceed with full-scale engineering development of the Trident II D5.

[26] The first submarine launch was attempted by USS Tennessee,[2] the first D-5 ship of the Ohio class, on 21 March 1989 off the coast of Cape Canaveral, Florida.

This first stage incorporates a solid propellant motor, parts to ensure first-stage ignition, and a thrust vector control (TVC) system.

[7] Both the first- and second-stage motors are connected by an interstage casing, which contains electronic equipment and ordnance for separation during flight.

The second stage also contains a motor made by Thiokol and Hercules Inc., parts to ensure the second-stage ignition, and a TVC system.

[29] The D-5's equipment section contains critical guidance and flight control avionics, such as the Mk 6 navigation system.

The equipment section also contains the third-stage TVC system, ordnance for ejecting from the second-stage motor, and the MIRV platform.

For example, in October 2020, Boeing was contracted for maintenance, rebuilding and technical services for the Trident II navigation subsystem,[34] and Northrop Grumman was contracted for engineering support and integration for the Trident II and relevant submarines at sites and shipyards from Sunnyvale, California, and Bangor, Washington, to Kings Bay, Georgia, and Cape Canaveral, Florida, among other locales.

[34] Peraton was contracted for program support services on the Trident II reentry subsystem,[35] and Systems Planning & Analysis Inc. was contracted for Trident II technical services, program support, assessments, special studies, and systems engineering.

[37] Within seconds, the missile breaches the surface of the water and the first-stage Thrust Vectoring Control (TVC) subsystem ignites.

When the nose fairing is clear of the missile, the third-stage TVC subsystem ignites, and ordnance separates the second-stage motor.

As the accuracy of a missile is dependent upon the guidance system knowing the exact position of the missile at any given moment during its flight, the fact that stars are a fixed reference point from which to calculate that position makes this a potentially very effective means of improving accuracy.

To prevent the PBCS correctional thrust from interfering with the RV when released, the equipment section initiates the Plume Avoidance Maneuver (PAM).

The MC4700 AF&F system (dubbed the "super fuze") significantly improves warhead kill probabilities against hardened targets such as silos or bunkers.

[45] In UK usage Trident II missiles are equipped with a warhead called Holbrook[46] and have a maximum yield of 100 kt.

[49] Some reports suggested that British warheads would receive the same arming, fusing and firing system (AF&F) as the US W76-1.