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The W88 Warhead

Intermediate yield strategic SLBM MIRV warhead

Last changed 1 October 1997

The W88 warhead belongs to the newest missile warhead family, sharing a design similar to the W87. It was designed for use on the Trident II (D5) SLBM. It combines a relatively high yield with increased accuracy to make it an effective hard target kill weapon. It is hardened against nuclear effects, and has enhanced safety features.

W88/Mk-5 Warhead/Reentry Vehicle Package
Yield475 Kt
Weight<800 lb ?
Length68.9 in
RV Base Diameter21.8 in
Nose Half Angle8.2 degrees
Number In Service400

Design Features

Two stage radiation implosion weapon.

RV CEP (circle error probability) is 300-400 feet

The basing mode of the W88 led to the adoption of lower criteria for warhead hardening and fire safety than the W-87 and thus lower weight. The reliance on stealth, and the absence of basing mode hardness (compared to fixed silos) reduced the need for shock hardening. The necessary compactness of the submarine carried Trident II, led to a design where the RVs are 'wrapped around' a high energy propellant upper stage. This in turn made a high degree of warhead fire safety pointless. The warhead thus uses a non-insensitive higher power explosive, and omits refractory insulation. The pit is not fire-resistant.

In the fall of 1990 Congress directed that a study be done on W-88 safety due to the use on non-insensitive high explosive. In December the study committee that redesigning the Trident II/W-88 system to use lower energy upper stage propellant, IHE, and a fire resistant pit, with reduced warhead loading (required under START in any case) would provide equal or superior performance and higher safety.


W88 warhead:
Contains oralloy (probably in second stage)
Uses PBX-9501 - an HMX-based plastic bonded explosive composition
Probable features:
Beryllium reflected plutonium fissile core for primary
Deuterium-tritium boosted
Lithium-6 (95% enrichment) deuteride fusion fuel

Mk-5 RV:
Alumium substructure, sheathed in graphite-epoxy composite
Carbon fiber fabric nose
Carbon fiber-phenolic resin heatshield

Delivery Method

Trident II (D-5) submarine launched ballistic missile (SLBM).

Safeguards and Arming Features

See Principles of Nuclear Weapons Security and Safety for explanations of these features.

Fuzing and Delivery Mode

Fuzing options probably the same as the W87
Radiation hardened microprocessor based "smart" fuzing system with:


Designed and developed by Los Alamos National Laboratory (LANL). The design is based on work done before March 1976 Threshold Test Ban Treaty. Full yield tests of candidate designs were completed by that date.

The Mk-5 RV is basically identical to the Mk-21 used with the W87

4000-5000 originally planned, production was prematurely terminated by FBI raid on Rocky Flats in November 1989. Although the possibility of resuming W-88 production using recycled pits from other weapons was examined, on 29 January 1992 Admiral Watkins, Sec. of Energy, directed that production be halted permanently.

W88 Development Schedule
March 1984 Development engineering begun at LANL
March 1986 Production engineering begun
September 1988 First production units completed
April 1989 Quantity production begun
November 1989 FBI raid on Rocky Flats shuts down production


Initial manufacture September 1988
Initial operating capability achieved June 1989
Total production: 400

The W-88 will remain in the active stockpile under START II, equipping Trident II (D-5) SLBMs.