Home search HEW Archive USA Arsenal Previous Disclaimer

The W87 Warhead

Intermediate yield strategic ICBM MIRV warhead

Last updated 1 September 2001

Mk-21 RVs mounted on a Peacekeeper (MX) bus. The W87 warhead itself is not visible.

Click for larger image

This image is from the Lawrence Livermore National
Laboratory Directorate of Nuclear Weapon website,
which was taken after the Wen Ho Lee scandal broke.

Click for larger image
This schematic of the W-87 is from the Cox Committee Report (the Report of the Select
Committee on U.S. NationalSecurity and Military/Commercial Concerns with the People's
Republic of China). Its accuracy is debatable but the features depicted make sense, and this
diagram prompted former weapon physicist Sam Cohen to remark:
... But what should be at least as disturbing is that the Cox report presents a beautiful
multicolored diagram (see graphic) that details the workings
and components of this highly classified warhead. That is, the Cox
report provides an extremely useful blueprint for use by Pakistan or India.

Insight Magazine, 16 July 1999

The W87 warhead belongs to the newest missile warhead family, sharing a design similar to the W88. It was designed for use on the Peacekeeper (MX) ICBM. 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.

W87-0/Mk-21 Warhead/Reentry Vehicle Package
Yield300 Kilotons (Upgradable to 475 Kt)
WeightWarhead: 440 - 600 lb;
RV/Warhead: >800 lb ?
Length68.9 in
RV Base Diameter21.8 in
Nose Half Angle8.2 degrees
Number In Service525

Design Features


Primary Stage

Secondary Stage

Mk-21 RV:

Delivery Method

Peacekeeper (MX) ICBM (LGM-118A). Each missile carries 10 W-87s, and is based in a hardened underground silo. As the Peacekeeper is retired under the provisions of START-II, these warheads will be used either to rearm Minuteman III missiles as single warhead missiles, or to equip Trident II D5 SLBMs.

Safeguards and Arming Features

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

Fuzing and Delivery Mode

Primary fuze is inertial (i.e. dead reckoning using guidance information)
Secondary dual mode S-band radar fuze (4 antennas) for airburst and surface/proximity fuzing
Fuzing options:


Designed and developed by Lawrence Livermore National Laboratory (LLNL)

Mk-21 RV formerly known as the ABRV (Advanced Ballistic Reentry Vehicle) developed by AVCO Systems Division. Heavier, but higher accuracy and lower cost than the Mk-12A. Tests of the Mk-21's hardness to nuclear effects were conducted in 1984-86: