Zumwalt Destroyers Lost Unaffordable Guns; Replacement Missiles Reportedly Two Years Late
The U.S. Navy’s three Zumwalt-class destroyers are caught between two weapon systems. Their original 155mm guns were removed after specialized ammunition approached $1 million per round, but the hypersonic missiles intended to support the ships’ new mission are reportedly two years behind schedule.
A July Defense News account of a Government Accountability Office assessment said the Navy was 24 months behind in modernizing the three destroyers for the Conventional Prompt Strike weapon. Launch capability has been installed, but the weapon and ship-integration effort remain incomplete. Planned flight testing from a destroyer, once scheduled for 2025, has moved to 2027.
The delay matters because this is not an incremental addition to an otherwise intact original armament plan. The Navy removed the two Advanced Gun Systems from each ship to make room for the hypersonic conversion. That leaves the small class in an extended transition from an abandoned gun-centered role to a missile capability that has yet to be fielded aboard it.
A 32-ship weapon built for three ships
Each Zumwalt originally carried two automated BAE Systems 155mm/62-caliber Advanced Gun Systems. Each gun was designed to fire 10 rounds per minute and store 335 rounds, giving the ship substantial magazine capacity for its planned land-attack mission.
The central constraint was ammunition compatibility. The guns were built around the Long Range Land Attack Projectile and could not use standard U.S. military 155mm shells without expensive redesign work. That specialized architecture became financially untenable after the planned Zumwalt fleet fell from 32 ships to three.
With only six shipboard guns requiring ammunition, the projectile lost the production volume over which its development and manufacturing costs were supposed to be spread. Its reported price approached $1 million per round. The problem was therefore not simply an expensive shell; it was a weapon-and-ammunition system whose economics depended on a fleet that was never built.
Redesigning the guns for conventional ammunition would also have required more engineering and procurement spending on a class of only three ships. The Navy instead chose to remove them and repurpose their space for a new strategic-strike mission.
The replacement is a wider integration problem
The missile conversion has encountered constraints on both sides of the interface. Modernizing a ship requires more than fitting launch tubes into the space left by the guns. Cabling, power, combat-system connections, maintenance access and ship configuration all have to match the new equipment. GAO found that work on the first ship required more cabling than initially anticipated after more existing cable was removed than planned.
The Zumwalt’s unusual architecture adds another boundary. Its integrated power system uses two Rolls-Royce MT30 gas turbines and two RR4500 generators, while its radar, combat and network systems are specific to a three-ship class. GAO described those unique systems as costly and difficult to sustain. That does not establish a single cause for the two-year missile delay, but it helps explain why modifications and maintenance on such a small, specialized fleet can be harder to standardize.
The missile program brings its own production and testing constraints. Testing has experienced setbacks since 2023, while manufacturing has faced quality-control issues and limited output. The weapon is being developed for both Navy and Army use, yet GAO found that the services do not adequately coordinate larger investment decisions affecting their shared production base.
GAO concluded that the effort “does not have a comprehensive strategy” for completing its goals. The Defense Department agreed with a recommendation to develop and regularly review a strategy coordinating investment decisions across the participating programs.
The ships retain substantial equipment beyond the removed guns, including an 80-cell Mk 57 Vertical Launch System, radar and sonar suites, and aviation facilities for MH-60R helicopters or MQ-8 Fire Scout unmanned aircraft. Those systems do not erase the central modernization gap, however. The decisive milestone will be successful shipboard testing of the hypersonic weapon now planned for 2027 because installed launch hardware alone does not restore the capability removed with the guns.
By David Whitaker — Associate editor for AMI’s aerospace and drone systems desk, translating flight systems, aircraft programs, spaceflight, and UAV developments into accessible technical stories.
