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The Department of Energy’s National Nuclear Security Administration (DOE/NNSA) officially authorized the start of the production engineering phase for the W88 Alteration (Alt) 370 program Feb. 22.

The alteration of the W88 nuclear warhead is part of NNSA’s multi-faceted strategy to ensure the American nuclear arsenal continues to be safe, secure, and effective. 

“Thanks to a team of talented scientists and engineers, we reached this important milestone in the W88 Alt 370 program on schedule,” said NNSA Administrator Lt. Gen. Frank G. Klotz (Ret). “This accomplishment marks an essential step in maintaining the nuclear capabilities required to deter attacks on the United States and its allies.”

As originally designed, the alteration included a new arming, fuzing, and firing subsystem and added a lightning arrestor connector to enhance nuclear safety and support future life extension program options.  In November 2014, the program expanded to include a complete replacement of the conventional high explosive main charges and associated components. 

“Achieving this milestone on time is a testament to the effective partnership between the NNSA National Security Labs, the production facilities, and the U.S. Navy,” said Phil Calbos, the acting deputy administrator for Defense Programs for NNSA. 

The W88 nuclear warhead entered the stockpile in late 1988 and is deployed on the Navy’s Trident II D5 Submarine-Launched Ballistic Missile (SLBM) system on Ohio-class ballistic missile submarines.  Deployed for almost three decades, several updates are required to address aging issues and to maintain its current state of readiness.

After four years of work in the development engineering phase of the program, this milestone marks the beginning of the production engineering phase prior to production.  The first production unit (FPU) of this weapon is planned for December 2019.

The W88 Alt 370 program is conducted by Los Alamos National Laboratory in Los Alamos, N.M.; Sandia National Laboratories in Albuquerque, N.M. and Livermore, Calif.; and the nuclear security enterprise production plants, including the Kansas City National Security Campus in Missouri; the Pantex Plant in Amarillo, Texas; and the Savannah River Site in Aiken, South Carolina.

Learn more about the W88 Alt 370.


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Established by Congress in 2000, NNSA is a semi-autonomous agency within the U.S. Department of Energy responsible for enhancing national security through the military application of nuclear science. NNSA maintains and enhances the safety, security, and effectiveness of the U.S. nuclear weapons stockpile without nuclear explosive testing; works to reduce global danger from weapons of mass destruction; provides the U.S. Navy with safe and effective nuclear propulsion; and responds to nuclear and radiological emergencies in the U.S. and abroad. Visit for more information.