English · العربية · فارسی · עברית · Русский · 中文 · Español · Français
Weapons 2026-03-21 7 min read

Trident II D5

Operational Submarine-launched ballistic missile (SLBM) Lockheed Martin

Specifications

DesignationTrident II D5
Also Known AsUGM-133A, Trident D5 LE
TypeSubmarine-launched ballistic missile (SLBM)
ManufacturerLockheed Martin
OperatorsUnited States; United Kingdom
Length13 m
Diameter2.11 m
Weight58500 kg
Range12000 km
SpeedMach 24+
GuidanceMk6 stellar-inertial guidance system with GPS updates
WarheadUp to 8 W76-1 (100 kT) or W88 (475 kT) MIRVed warheads
PropulsionThree-stage solid propellant rocket
First Tested1987
First Deployed1990
Unit Cost$30 million

Overview

The Trident II D5 is a submarine-launched ballistic missile (SLBM) deployed by the United States and the United Kingdom. As the most advanced and reliable SLBM in service, it forms a critical component of their nuclear deterrent strategies. Carried aboard Ohio-class and Vanguard-class submarines, each missile can deliver up to eight independently targetable warheads, posing a significant threat to any adversary. The Trident II D5's stealth and range, combined with its accuracy and destructive power, make it a formidable weapon system. Its continued operational status and planned life extension programs ensure its relevance in maintaining strategic stability in an increasingly complex geopolitical landscape, including deterring potential aggression from Iran and its allies.

Development History

The Trident II D5 program began in the 1980s as a successor to the Trident I C4 missile. Lockheed Martin was selected as the prime contractor, and the first test flight occurred in 1987. The D5 incorporated advanced technologies, including a more accurate guidance system and a higher payload capacity. Initial deployments began in 1990 aboard the Ohio-class submarines. Continuous upgrades and improvements have been implemented throughout its service life, including the D5 Life Extension Program (LEP), which aims to extend the missile's operational lifespan to 2040. The LEP focuses on replacing aging components and enhancing the missile's performance and reliability, ensuring its continued effectiveness as a strategic deterrent.

Technical Deep Dive

The Trident II D5 is a three-stage, solid-propellant missile. Its Mk6 guidance system combines stellar-inertial navigation with GPS updates, providing exceptional accuracy. The missile's post-boost vehicle (PBV) deploys multiple independently targetable reentry vehicles (MIRVs), each carrying a W76-1 or W88 nuclear warhead. The W76-1 warhead has a yield of approximately 100 kilotons, while the W88 warhead has a yield of 475 kilotons. The missile's propulsion system consists of three solid-propellant rocket motors, providing the necessary thrust to achieve its intercontinental range. The missile is ejected from the submarine launch tube using high-pressure gas before the first-stage motor ignites. The D5's design emphasizes reliability and maintainability, contributing to its impressive track record of successful test launches.

Combat Record

1990-Present confirmed
Continuous Strategic Deterrence Patrols
The Trident II D5 has been continuously deployed on strategic deterrence patrols by the US and UK navies, contributing to nuclear deterrence. No combat use.
February 2005 confirmed
US Navy test launch off Florida coast
Successful test launch of an unarmed Trident II D5 missile from the USS Alaska (SSBN-732). Demonstrated system reliability.
June 2016 reported
UK Trident II D5 test launch anomaly
A UK Trident II D5 test launch experienced an in-flight anomaly. The missile veered off course. The incident was classified at the time.

Tactical Role

The Trident II D5 serves as a cornerstone of nuclear deterrence. Its primary tactical role is to ensure a credible second-strike capability. By being deployed on submarines, the missile is virtually invulnerable to a first strike, guaranteeing a retaliatory response. In the context of potential conflict with Iran, the Trident II D5 acts as a deterrent against large-scale aggression or the use of weapons of mass destruction. The threat of nuclear retaliation is intended to prevent escalation and maintain strategic stability.

Strengths & Weaknesses

Exceptional reliability: The Trident II D5 boasts an unparalleled record of over 180 consecutive successful test launches, making it the most reliable SLBM ever developed.
Submarine-based survivability: Deployed on stealthy submarines, the Trident II D5 is virtually invulnerable to a first strike, ensuring a credible second-strike capability.
High payload capacity: Each missile can carry up to eight independently targetable warheads, allowing for a wide range of targets to be engaged.
Extended range: With a range of 12,000 kilometers, the Trident II D5 can reach targets across the globe from its submarine launch platforms.
Accurate guidance: The Mk6 stellar-inertial guidance system, combined with GPS updates, provides exceptional accuracy, ensuring a high probability of target destruction.
High cost: At approximately $30 million per missile, the Trident II D5 is an expensive weapon system, requiring significant investment for procurement and maintenance.
Aging platforms: The Ohio-class submarines, which carry the Trident II D5, are aging, and the Columbia-class replacement program has faced delays.
US dependency: The United Kingdom relies entirely on the United States for the supply and maintenance of its Trident II D5 missiles, creating a dependency vulnerability.
Limited flexibility: As a purely strategic weapon, the Trident II D5 is not suitable for conventional warfare or limited-scale conflicts.
Potential for escalation: The use of nuclear weapons carries the risk of escalation to a full-scale nuclear war, making it a weapon of last resort.

Variants

VariantDifferencesStatus
Trident I C4Predecessor to the D5, with shorter range and lower payload capacity. Now retired.Retired
Trident II D5 Life Extension Program (LEP)Upgraded version with modernized components and extended service life to 2040.Operational

Countermeasures

Countering the Trident II D5 is exceptionally challenging due to its submarine-based deployment. Anti-submarine warfare (ASW) capabilities, including advanced sonar and surveillance systems, are essential for detecting and tracking the submarines. However, the vastness of the ocean and the submarines' stealth capabilities make this a difficult task. Ballistic missile defense (BMD) systems could potentially intercept the missiles in flight, but the MIRV capability complicates interception efforts. Ultimately, the most effective countermeasure is deterrence, maintaining a credible threat of retaliation to discourage the use of nuclear weapons.

Frequently Asked Questions

What is the range of the Trident II D5 missile?

The Trident II D5 has a range of approximately 12,000 kilometers (7,456 miles). This intercontinental range allows it to strike targets across the globe from its submarine launch platforms.

How many warheads can a Trident II D5 carry?

The Trident II D5 can carry up to eight independently targetable reentry vehicles (MIRVs), each carrying a W76-1 or W88 nuclear warhead. The W76-1 has a yield of 100 kilotons, while the W88 has a yield of 475 kilotons.

Which countries operate the Trident II D5?

The Trident II D5 is operated by the United States and the United Kingdom. It is deployed on Ohio-class submarines in the US Navy and Vanguard-class submarines in the Royal Navy.

How accurate is the Trident II D5 missile?

The Trident II D5 is exceptionally accurate, thanks to its Mk6 stellar-inertial guidance system with GPS updates. This high accuracy ensures a high probability of target destruction.

How reliable is the Trident II D5?

The Trident II D5 is considered the most reliable submarine-launched ballistic missile ever developed, with a record of over 180 consecutive successful test launches. This exceptional reliability is a key factor in its effectiveness as a strategic deterrent.

Related

Sources

Trident II D5 Fact Sheet U.S. Navy official
The Trident D5 Life Extension Program: An Assessment Congressional Budget Office official
Nuclear Weapons Databook, Volume VIII: U.S. Nuclear Warhead Production Natural Resources Defense Council academic
Trident missile test fails, raising questions about UK nuclear deterrent The Guardian journalistic

Related News & Analysis