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Lockheed Martin UGM-133 Trident II

The UGM-133 Trident II D-5 is the ultimate SLBM (Submarine-Launched Ballistic Missile) of the U.S. Navy. Attributed with very long range, a high-precision guidance system, and a MIRV (Multiple Independent Reentry Vehicle) warhead, it is probably the most important part of the current nuclear arsenal of the United States.

When the U.S. Navy and Lockheed studied the possibility of an ULMS (Undersea Long-Range Missile System) in the early 1970s, it was decided to develop an improved UGM-73 Poseidon C-3 missile first (this evolved into the UGM-96 Trident I C-4), to be followed later by a much enlarged missile to be deployed on a new class of strategic missile submarines. The first ship of this new SLBM class, the USS Ohio (SSBN-726), was commissioned in November 1981. This ship, as well as the next seven Ohio class SSBNs, was fitted with Trident I missiles, but Lockheed had already begun design of the new D-5 SLBM to make full use of the Ohio's large missile tubes. The formal development contract for the new missile, by then called Trident II, was issued in October 1983. The missile designation UGM-133A was assigned in early 1986, and it's possible that an interim designation of UGM-96B was used before that date. The first Trident II launch occurred in January 1987, and the first submarine launch was attempted by USS Tennessee (SSBN-734, the first D-5 ship of the Ohio class) in March 1989. The latter failed because of problems with the first stage engine nozzle, and these problems delayed the IOC (Initial Operational Capability) of the Trident II until March 1990.

Photo: U.S. Navy

The UGM-133A Trident II D-5 SLBM is a significantly enlarged development of the UGM-96 Trident I C-4. It employs many of the advanced design features of the latter (including the extendable aero-spike, light-weight motor casings, and high-density fuel), and the larger size leads to an increased range of up to 11100 km (6000 nm). This range enables the Trident II to reach almost every strategic target in the Northern hemisphere when launched from SSBNs sitting in U.S. ports. The MK 6 stellar/inertial navigation system is able to receive GPS (Global Positioning System) updates, thereby increasing accuracy to that of a land-based ICBM, about 90 m (300 ft) CEP (compared to 380 m (1250 ft) for the C-4). The warhead section consists of six (or 14 in a maximum payload shorter-range configuration) MK 5 independent reentry vehicles, each one carrying a 475 kT W-88 thermonuclear warhead. Alternatively, the UGM-133A can also be fitted with the MK 4 reentry vehicles of the UGM-96A Trident I carrying 100 kT W-76 warheads.

Photo: Russ Underwood,
Lockheed Martin Missiles & Space
Photo: Lockheed Martin Missiles & Space
From left: UGM-133A, UGM-96A UGM-133A

The ten newest SSBNs of the 18 Ohio class ships are currently operational with the Trident II D-5, each SSBN having 24 missile tubes. Of the eight older submarines originally equipped with Trident I C-4, four have been converted to the D-5 (the other four were withdrawn from strategic service and converted to SSGNs). With the possible conversion of the LGM-30G Minuteman III ICBMs to single-RV warheads, and the retirement of the LGM-118 Peacekeeper, the Trident II might soon be the only MIRVed strategic missile in the US nuclear inventory, and therefore become the most important deterrance weapon. Production of the UGM-133A is continuing, and more than 400 missiles have been built so far of a planned total of 540.

Image: Lockheed Martin Missiles & Space
SLBM family: UGM-27A, UGM-27B, UGM-27C, UGM-73A, UGM-96A, UGM-133A


Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!

Data for UGM-133A:

Length13.58 m (44 ft 6.6 in)
Diameter2.11 m (6 ft 11 in)
Weight58900 kg (130000 lb)
Range11100 km (6000 nm)
Speed> 6000 m/s (20000 ft/s)
Propulsion1st and 2nd stage: Hercules/Thiokol solid-fueled rocket
3rd stage: United Technologies Corp. solid-fueled rocket
Warhead6x W-88 thermonuclear (475 kT) in 6x MK 5 RV

Main Sources

[1] James N. Gibson: "Nuclear Weapons of the United States", Schiffer Publishing Ltd, 1996
[2] Norman Friedman: "World Naval Weapons Systems, 1997/98", Naval Institute Press, 1997

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Last Updated: 18 January 2008