Introduction

The Poseidon Submarine-Launched Ballistic Missile (SLBM) played a crucial role in the U.S.’s nuclear strategy during the Cold War. It signified the U.S.’s choice to place most of its nuclear warheads in its sea-based deterrent force. This decision was part of the Triad deterrent strategy.

Deployment

In 1971, the deployment of the Poseidon C3 SLBM began. It coincided with the phase-out of the Polaris A2 SLBM in 1974 and the Polaris A3 in 1982.

The U.S. Navy converted thirty-one nuclear ballistic missile submarines (SSBNs) of the Lafayette, Madison, and Benjamin Franklin classes to carry the new missile. The following table displays the conversion dates:

By 1978, the U.S. had thirty-one Lafayette-class SSBNs with Poseidon C-3 missiles. These submarines carried 496 Poseidon C3 missiles. These missiles contained 4,960 W68 thermonuclear warheads. Each warhead within its own Mk 3 RV.

This was a significant increase. The Poseidon’s peak deployment had 4,960 warheads. In contrast, the Polaris had a peak of only 656 warheads. This means the Poseidon had over 650% more warheads than the Polaris.

However, by 1991, the Poseidon C3 SLBM was phased out. This phase-out happened alongside the start of the Trident I C4 SLBM deployment in 1979. Then, in 1990, the Trident II D5 SLBM was deployed. This was around the time the last Poseidon SLBM was retired. Two years after the Poseidon was phased out, the last Lafayette-class SSBN was also withdrawn. Its Trident I C4 missiles moved to the Ohio-class SSBNs.

SSBNs, SLBM Launchers & Warheads

The table below details the Poseidon C3 deployment from 1971 to 1991 (as of December 31):

Further reading

• United States Submarine-Launched Ballistic Missiles (SLBM)
• Polaris A-2 (UGM-27B)
• Polaris A-3 (UGM-27C)
• Trident I C-4 (UGM-96)
• Trident I C-4 Missile Deployment (1979-2004)
• Trident II D-5 (UGM-133A)

Bibliography

• Evolution of the U.S. Sea-Based Nuclear Missile Deterrent: Warfighting Capabilities by George J. Refuto, 2011