The U.S. Navy has validated a method for launching hypersonic missiles from warships, but the engineering required to make it work demands oversized vertical tubes that will reshape the physical profile of American destroyers. The Conventional Prompt Strike program, or CPS, relies on a cold-gas ejection system that pushes each missile clear of the ship before its rocket motor ignites, a safety requirement that dictates the size and structure of the launch hardware. As the Pentagon works to field sea-based hypersonic weapons amid growing competition with China and Russia, the tubes themselves have become a defining feature of the effort and a source of both tactical promise and logistical risk.
Cold-Gas Ejection Explains the Tube Size
Hypersonic missiles are far larger and faster than the cruise missiles that currently fill the Navy’s standard vertical launch cells. The CPS weapon cannot simply be dropped into an existing launcher. Instead, the Navy developed what it calls a cold-gas launch approach that uses compressed gas to eject the missile to a safe distance from the ship before first-stage ignition. That sequence protects the vessel and its crew from the extreme heat and thrust of a hypersonic booster firing at close range. The tubes must be tall and wide enough to house the full missile body, contain the gas charge, and guide the weapon on a clean vertical path during ejection.
The Navy said it validated the approach in testing, and Defense Department reporting describes the cold-gas launch method as a step toward eventual shipboard employment. Public reporting has also described an upcoming CPS flight test in 2025, but the Navy has not publicly detailed all conditions or operational milestones for an at-sea “end-to-end” demonstration. The cold-gas method is not new in concept; submarine-launched ballistic missiles have used steam ejection for decades. But adapting it to a surface combatant, where the tubes sit exposed on deck rather than submerged in a pressure hull, introduces distinct structural and thermal challenges that drive the hardware’s bulk.
Zumwalt Destroyers and the Four-Tube Retrofit
The first warship slated to carry CPS is a Zumwalt-class stealth destroyer, a ship originally designed for shore bombardment but now being repurposed as a hypersonic strike platform. The retrofit concept calls for four large tubes, with public reporting describing a planned multi-missile capacity per tube that could give a single destroyer a magazine in the low double digits. That capacity is modest compared to the 96 cells in a standard Arleigh Burke destroyer’s vertical launch system, but the striking power per round is far greater. A single CPS weapon can travel thousands of miles at speeds exceeding Mach 5, reaching heavily defended targets that slower cruise missiles might not survive to hit.
The strategic logic behind this retrofit is straightforward: the United States currently has no fielded sea-based hypersonic weapon, while both China and Russia have tested or deployed their own variants. Placing even a small number of hypersonic missiles on a stealth destroyer changes the calculus for adversaries operating in the Western Pacific or other contested waters. Yet the physical reality of bolting four giant tubes onto a warship originally designed for a different mission raises questions about weight distribution, radar signature, and how quickly crews can reload at sea, if reloading is even practical in a combat scenario.
Budget Pressure and Production Scale
Congress has invested heavily in getting CPS to the fleet. The fiscal year 2024 defense appropriations bill, documented in Senate Report 118-81, identified funding for CPS across both Weapons Procurement, Navy and Research, Development, Test, and Evaluation accounts. That legislation specified lot 1 low-rate initial production of eight all-up rounds alongside continued flight testing. Eight rounds is a small batch, enough to arm portions of one or two ships, but it signals that the program has moved past pure research into early manufacturing.
The Congressional Research Service, in its report on FY2026 defense budget funding for selected weapon systems, places CPS within the Department of Defense’s broader hypersonics portfolio. That portfolio spans Army, Navy, and Air Force programs, but CPS is the only one designed specifically for surface-ship launch. The cross-service spending context matters because it shows how much of the Pentagon’s hypersonic investment is riding on the Navy’s ability to prove that oversized tubes on a destroyer deck can reliably send weapons downrange. If CPS falters, it could set back the Navy’s sea-based hypersonic effort and complicate the Pentagon’s broader plans for a surface-ship option within its hypersonics portfolio.
Schedule Risk and Testing Gaps
The Government Accountability Office has flagged serious concerns about whether the Pentagon can deliver hypersonic weapons on time. In its annual weapon systems assessment, report GAO-24-106831, the auditing agency found that the Department of Defense is not yet well positioned to field major systems with speed. The report covers acquisition status, schedule risk, and testing and integration issues across dozens of programs, and hypersonics rank among those facing the steepest hurdles. For CPS specifically, the gap between proving a cold-gas launch in a controlled test and operating a combat-ready weapon aboard a ship at sea remains wide.
One potential risk is the tactical exposure created by the cold-gas ejection sequence itself. During the seconds between tube ejection and booster ignition, the missile is briefly unpowered after leaving the tube. In a contested environment where adversaries field anti-ship missiles and electronic warfare systems, that short window could be viewed as a vulnerability, though the Navy has not publicly provided detailed assessments. The Navy has not publicly released risk assessments addressing this scenario, and the available institutional sources do not include declassified data on how the system performs under electronic jamming or near-miss conditions. Comparisons to submarine ejection systems can be imperfect: submarines typically launch from concealment underwater, while a surface ship launch is inherently more observable. What that means tactically depends on classified performance data the Navy has not released publicly.
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*This article was researched with the help of AI, with human editors creating the final content.
