The British Strategic Systems Programs

III. TRIDENT II D5 Life Extension


United States (U.S.) assistance and support to the United Kingdom’s (U.K.) strategic systems programs are covered by the POLARIS Sales Agreement, which was a direct result of the now-historic meeting at Nassau in December 1962 between President Kennedy and Prime Minister MacMillan. SSP has additional responsibilities related to the British Strategic Systems Programs.

Under the terms of the Sales Agreement, the U.S. sold POLARIS missiles (less warheads) to the U.K. In addition to the missiles, the subsystems that make up the weapon system were also sold. The British built their own nuclearpowered submarines to house the weapon system and provided their own warheads.

In July 1980 the U.K. requested, and the U.S. agreed to, the sale of Trident I missiles (less warheads), equipment, and services to the U.K. On 30 September 1980, the U.S. and U.K. letter agreements were formally implemented by an exchange of diplomatic notes that incorporated the TRIDENT sale into the POLARIS Sales Agreement.

In light of the U.S. DoD decision to develop and procure the TRIDENT II (D5) missile, the U.K., in order to maintain commonality with the U.S., requested in March 1982 that the U.S. sell them the TRIDENT II instead of the TRIDENT I. The U.S. agreed to this substitution in an exchange of letters between President Reagan and Prime Minister Thatcher.

The Director, SSP, is the U.S. project officer for this program, and the Chief Strategic Systems Executive (CSSE) is the British project officer. A small British staff from CSSE is assigned to SSP, and a U.S. liaison officer from SSP is assigned to duty in the British Ministry of Defense to ensure prompt and effective support to the U.K. programs. A Joint Steering Task Group, chaired by the respective Admirals in turn, meets alternately in London and Washington three times a year.

The U.K. POLARIS force was comprised of four SSBNs designed by Vickers Shipbuilding and Engineering Ltd. (VSEL), Barrow-in- Furness, and used a U.S. designed missile section. Similar in size to the USS LAFAYETTE, the Royal Navy (RN) POLARIS submarines had the distinctive whale-like hull adopted by the RN for their first-generation SSNs, with the diving planes positioned on either side of the bow rather than on either side of the sail as with U.S. FBM submarines. Powered by the British pressurized water nuclear reactors built by Rolls Royce and Associates, each submarine carried 16 POLARIS A3 missiles. Two of the submarines were built by Vickers Shipbuilding at Barrow and two at Cammell Laird of Birkenhead.

The force operated from a submarine base at Faslane on the Clyde in Scotland, with an associated Armament Depot at nearby Coulport. Located on the base, which included accommodation and recreational facilities and amenities, was the Royal Navy’s POLARIS Weapon System School, commissioned 10 June 1966.

The end of the initial outfitting period was marked on 13 December 1969. At that time, the U.K. had their operating base at Faslane built and all four POLARIS submarines accepted for service. The first U.K. submarine, HMS RESOLUTION, was launched in September 1966 and visited Cape Canaveral in February and early March 1968, where both Port and Starboard crews successfully launched a POLARIS A3 missile into a downrange target area. HMS RESOLUTION made her first deterrent patrol in June 1968. HMS RENOWN was launched in February 1967, HMS REPULSE in November 1967, and HMS REVENGE in March 1968.

In the early 1970s, the U.K. embarked on an extensive program, known as Chevaline, to improve the effectiveness of the A3 missile system by modifying its front end. In the 1980s, new A3 first- and second-stage motors were procured by the U.K. to replace aging A3 stocks; the new motors were designated A3R. The U.K.’s POLARIS force was phased out in 1996 and has been replaced by a Trident force.


The U.K.’s Trident force is based on four VANGUARD Class SSBNs, each capable of carrying 16 Trident II (D5) missiles. The U.K. submarine was designed by VSEL, Barrow-in-Furness. The first submarine, HMS VANGUARD, was launched in March 1992. Both her crews successfully test fired unarmed Trident II (D5) missiles at the Eastern Test Range in 1994.

HMS VANGUARD deployed on her first operational patrol in December 1994. The second boat, HMS VICTORIOUS, deployed in January 1996. The third ship, HMS VIGILANT, deployed in February 1998. The fourth and final submarine, the HMS VENGEANCE, deployed in early 2001. By the 45th Anniversary of SSP all VANGUARD Class submarines had successfully launched one Trident II (D5) missile during a Demonstration And Shakedown Operation (DASO). Like POLARIS, VANGUARD Class submarines use a U.S. designed missile section. A second-generation Rolls Royce and Associates pressurized water nuclear reactor provides the power.

TRIDENT II D5 Life Extension

The TRIDENT II (D5) Life Extension Program extends the service life of the TRIDENT II (D5) Strategic Weapons System to support the extended service life of the OHIO Class Submarine to 45 years. This program, the result of a Navy/OSD study, is designed to extend the production and sustain the effectiveness of the TRIDENT II Strategic Weapons System to 2042. The 2001 Nuclear Posture Review (NPR) supported full funding for D5 Life Extension and the Navy revalidated this low rate production continuity acquisition strategy in a report to Congress in 2002. The TRIDENT II (D5) Life Extension Program will be accomplished through upgrades to missile and guidance electronics to mitigate obsolescence, and through the continued production of critical missile components


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