GAO Finds Delays, Cost Overruns in Navy Hypersonic Missile Refit

Zumwalt Retrofit Falls Further Behind Schedule

According to a report by The Maritime Executive, a new Government Accountability Office (GAO) audit has revealed significant delays and cost growth in the U.S. Navy’s program to arm its three Zumwalt-class destroyers with Conventional Prompt Strike (CPS) hypersonic missiles. The retrofit effort, which involves replacing the ships’ original 155mm Advanced Gun Systems with missile launch cells, is now running about two years behind its original timeline.

The Zumwalt class was originally conceived for shore bombardment using specialized long-range guns, but that mission became impractical once the class was cut from a planned 32 ships to just three, driving the cost of custom ammunition rounds up to $800,000-$1 million each. With the gun program scrapped, the Navy pivoted to converting the ships into hypersonic missile platforms instead. Lead ship USS Zumwalt (DDG 1000) has already had its gun mounts replaced with four missile cells, each holding three CPS rounds, while sister ships DDG 1001 and DDG 1002 are undergoing or awaiting similar work.

Structural Work and Reliability Concerns

Beyond the weapons swap, the yard periods include extensive modifications: removal of outdated computer equipment, expanded crew berthing, relocated air intakes to cut exhaust ingestion, software upgrades, and conversion of ballast tanks to extend fuel range. Flight testing of the integrated CPS system aboard DDG 1000 is now targeted for fiscal year 2027, after which the missile would move into low-rate production for the remaining hulls.

The GAO audit points to unplanned cabling work, complex electrical fixes, and funding delays as key drivers of the schedule slip, with DDG 1001’s retrofit yet to even begin. The audit also flags long-standing reliability problems with the Zumwalt’s integrated power system, which distributes power to propulsion, ship systems, and future weapons such as lasers or railguns. Numerous serious casualties tied to this system have occurred, some requiring three-month lead times for replacement parts, forcing the Navy to strip components from DDG 1002 to keep the other two hulls running—further delaying that ship’s activation.

Missile Production Can’t Keep Pace

The CPS missile itself is proving difficult to manufacture at the required rate. Testing anomalies in June 2025 pushed DDG 1000’s first flight tests to 2027, compounded by funding cuts that limited available test missiles. GAO found that the contractor’s production facility can currently turn out only six to seven rounds a year, well short of the twelve needed to stabilize output. Cited problems include faulty outer coating application, overly complex work instructions, incomplete assembly kits, high staff turnover, weak materials controls, and inconsistent quality assurance.

Compounding matters, Navy program managers reportedly have limited authority to direct fixes to the production line due to contract terms barring “co-direction” of the work, while coordination with the Army—which is procuring its own CPS missiles and oversees several production steps—has been weak, according to GAO.

A Costly Capability

The Navy estimates the CPS program’s total lifecycle cost at $41 billion for 224 missiles and associated launch infrastructure, working out to roughly $180 million per round over its service life, with a unit price of $67 million—about 20 times the cost of the stealthy Long Range Antiship Missile. GAO warned that continued poor planning and interservice coordination could push these figures even higher.

What It Means for Fleet Readiness and Oversight

While this program sits squarely in naval procurement rather than commercial shipping, it illustrates a pattern familiar to anyone involved in vessel condition assessment: complex retrofit projects that touch structural, electrical, and propulsion systems simultaneously carry compounding risk, and problems in one subsystem cascade into others. The practice of cannibalizing parts from a sister ship to keep two hulls operational is a stopgap that surveyors and technical managers would flag as a red flag in any commercial fleet audit—deferred maintenance debt that eventually surfaces as extended downtime. For ship owners and managers watching major retrofit or conversion projects of their own, the GAO findings are a reminder that independent, rigorous inspection and milestone verification during major yard periods can catch integration and quality issues long before they compound into multi-year schedule slips and ballooning costs.

Reviewed by Ibrahim Halil Ceylan, Marine Surveyor at Apeks Marine.