The UGM-133 Trident II D5 is a three-stage, solid-fueled submarine-launched intercontinental-range ballistic missile. The Trident D5 missile is deployed by both the United States and United Kingdom on their respective Ohio- and Vanguard-class nuclear missile submarines.
The UGM-133 Trident II D5 is the U.S. Navy’s latest generation submarine-launched ballistic missile (SLBM). It improved upon earlier SLBMs including the Polaris, Poseidon, and Trident I C4. These programs, categorized as US Fleet Ballistic Missile technologies, began in the mid-1950s. The Navy began developing the Trident D5 in March 1980. The first test launch took place in January 1987 and the first sea trial, which was unsuccessful, occurred in March 1989. The Trident D5 entered service in 1990.1
The Trident D5 was originally intended to significantly increase range compared to the first-generation Trident I C4. However, the Navy eventually shifted its emphasis from increasing range to improving accuracy as the Trident D5’s counterforce mission became a focal design point.2
The Trident D5 has undergone extensive improvement programs. More accurate GPS systems have been tested on Trident missiles since 1993 and an earth penetrator version was considered in 1994 to attack underground facilities. Improved air-burst fuses were considered for the Mk 4 RV in 1998. New third-stage propellant motors were developed and tested and will likely be included in future versions. An extensive upgrade for 300 missiles is planned in 2020 in order to upgrade them to the Trident D-5A or D-5LE versions with improved capabilities and an extended service life to 2042.3
In the mid-2000s, the Defense Department requested to deploy conventionally-armed Trident D5 missiles to satisfy requirements for its Conventional Prompt Global Strike capability. However, Congress rejected funding for this program.4
In June 2002, the Navy initiated the D5 Life Extension to replace aging missile parts and extend missile life from 30 to 44 years.5
In January 2021, VADM Johnny Wolfe announced the Navy would start the Trident D5 Extension Life II upgrade this year.6 The second life extension program seeks to increase the Trident D5’s lifespan for another 60 years to deploy through the 2080s.7
Since the Trident’s design completion in 1989, the U.S. Navy has successfully conducted over 160 missile test launches.8
The Trident D5 has a range of 12,000 km and can carry a payload as large as 2,800 kg. Its payload carries a Post-Boost Vehicle (PBV) which can carry up to 12 Reentry Vehicles (RVs), though New START limits the number to eight. These RVs can be either the Mk 4 with a W76 100 kT yield warhead or the Mk 5, which has a W88 475 kT yield warhead. This firepower makes the Trident D5 the first U.S. submarine-based missile capable of destroying hardened targets. The system uses an inertial navigation system combined with a stellar reference system that provides an accuracy of 90 m CEP. The missile measures 13.42 m in length, 2.11 m in diameter, and weighs 59,090 kg at launch. It is three-staged and uses solid-propellant.9
The 2018 Nuclear Posture Review highlighted the need for a new low-yield Trident missile to deter adversary use of similarly low-yield nuclear weapons.10 Congress appropriated $65 million in FY2019 and $10 million in FY2020 to fund the new warhead, which was designated the W76-2. The Navy deployed a number of W76-2s by February 2020.11
The United States maintains 14 Ohio-class submarines, with two in repair at any time. Each of these SSBNs carries 20 Trident D5s for a total arsenal of 240 SLBMs. A 2016 report notes that nine Ohio-class submarines are deployed in the Pacific and five in the Atlantic.12
The Navy’s forthcoming Columbia-class submarine will equip the Trident D5 as it enters service in the early 2030s. The Navy plans to deploy 12 Columbia-class submarines, each carrying 16 Trident D5 missiles in four “quad packs.”13
In 1994, the United Kingdom began equipping the Trident D5 aboard its four Vanguard-class missile submarines. Each submarine can carry 16 missiles and are equipped with UK warheads believed to be similar to the W76 100 kT US warheads. An unknown number of the missiles are also planned for deployment for non-strategic roles with 10 kT warheads. A 1999 UK statement limited the number of warheads to be deployed on each submarine to 48, an average of 3 warheads per missile.14 In July 2016, Parliament voted to approve new SSBNs to preserve the UK nuclear deterrent, ensuring that Trident will be deployed into 2050s.15
The UK Navy’s forthcoming Dreadnought-class submarine will equip the Trident D5 as it enters service in the early 2030s. The Navy plans to deploy two Dreadnought-class submarines.