ISC Defence Intelligence title card. A rights-cleared public-domain image of USS Zumwalt was not available at publication; illustrative only.

GAO Finds the US Navy's Conventional Prompt Strike Hypersonic Weapon Two Years Late on the Zumwalt Class

A July 2026 US Government Accountability Office report, GAO-26-107974, finds the Navy's plan to arm its three Zumwalt-class destroyers with the Conventional Prompt Strike boost-glide hypersonic weapon is running 24 months late. The first launch from USS Zumwalt has slipped to the third quarter of fiscal year 2027, and each round is estimated at about 67 million US dollars.

Technical Summary

Conventional Prompt Strike (CPS) is the United States Navy's sea-launched boost-glide hypersonic weapon. A large solid rocket motor booster carries a Common Hypersonic Glide Body (C-HGB) into the upper atmosphere, after which the glide body separates and manoeuvres toward its target at speeds above Mach 5. The Navy shares the missile and glide body with the US Army's land-based Long-Range Hypersonic Weapon; the naval version uses a cold-gas launch that ejects the round from its canister before the rocket motor ignites clear of the ship, while the Army fires from a hot-launch land system. The Zumwalt class, three ships built as land-attack surface combatants, was selected in 2022 as the first surface host.

In its July 2026 report, GAO-26-107974, the Government Accountability Office (GAO) assessed the programme as running about 24 months behind schedule. USS Zumwalt was 94 percent through its modernisation as of January 2026 but remained late because of unplanned work, and the first CPS flight from the ship has moved from 2025 to the third quarter of fiscal year 2027. Installing CPS required cutting Large Missile Vertical Launch Tubes into the hull, fitting weapons-control equipment and removing the two 155 mm Advanced Gun System mounts, whose guided Long Range Land Attack Projectile had been cancelled years earlier over cost.

The Government Accountability Office put the Conventional Prompt Strike lifecycle estimate at about 41 billion US dollars for 224 missiles, roughly 67 million dollars each, while the missile prime can build only six to seven rounds a year against a target rate of twelve. ISC assessment of GAO-26-107974, July 2026

The Conventional Prompt Strike battery is planned across all three Zumwalt-class destroyers, with USS Zumwalt the first to receive it, followed by USS Michael Monsoor and the future USS Lyndon B. Johnson, each fitted with a twelve-round complement (Naval News).

Conventional Prompt Strike is also planned for the Virginia-class Block V submarines from about 2028, which places the surface and subsurface programmes in competition for the same limited All Up Round production (Naval News, SNA 2025).

Analysis of Effects

The intelligence question in this report is industrial, not operational. GAO records lifecycle cost rising from about 31 billion US dollars for 262 missiles in 2020 to about 41 billion for 224 in 2024, with a unit cost of 63 to 71 million dollars and an average near 67 million as of April 2026. Against that, Lockheed Martin, the missile-body prime, can currently produce six to seven all-up rounds a year, below the twelve-per-year rate GAO says is needed to stabilise production. The cited causes are labour-intensive assembly, thermal-protection coating difficulty, complex work instructions, inspection problems, incomplete assembly kits and workforce turnover, with about a year before a new hire works independently.

For the weapons reader the constraint is characteristically hypersonic. The pacing items are the two-stage solid rocket motor booster and the glide body's thermal protection, not the airframe, and both are slow to qualify and hard to accelerate. A production floor of six to seven rounds a year means three destroyers, plus the Army battery fielding the same round, will compete for a supply measured in single-digit tens per year. At about 67 million US dollars a round, CPS is a scarce, high-value effect to be reserved for the hardest, time-critical targets, not a volume weapon. The ship-integration bill compounds the picture: the Zumwalt modernisation estimate rose from 1.8 billion to at least 2 billion dollars, with 230,000 hours of unplanned cabling work added in August 2025.

Personnel and Safety Considerations

The naval cold-gas launch is itself a safety design choice. Ejecting the round from its canister by cold gas and igniting the solid rocket motor booster only after the missile is clear of the deck reduces the efflux and overpressure hazard to the ship compared with a hot in-tube ignition. The dominant energetic aboard is the two-stage booster propellant, most plausibly United Nations Hazard Division 1.3 in its stored configuration, which sets the magazine quantity-distance and insensitive-munitions case for a large round carried in Large Missile Vertical Launch Tubes. The conventional glide-body payload mass and net explosive quantity are not disclosed. GAO also flags reliability concerns in the class's unique integrated power system, which is a platform-availability issue rather than a munitions-safety one but bears on whether a loaded ship can deploy.

Data Gaps

Open sources do not establish: the CPS glide-body warhead type, mass and net explosive quantity; the booster propellant type, mass and confirmed hazard division; the achieved terminal speed and range of the fielded round; the flight-test success record to date; the firm production ramp date to twelve rounds a year; and whether the Navy will replace the Zumwalt class's unique combat and power systems, which GAO estimates could add 1 to 2 billion US dollars. Hazard-division and net-explosive-quantity values here are estimates pending official data and are not independently verified.

Corrections & updates welcome. If you hold open-source data that refines or corrects any parameter in this article, please contact [email protected] citing the specific claim and your source. Verified corrections will be incorporated and credited in the revision history. AI-assisted technical assessment based on open-source material. Not a formal intelligence product.