The US Navy wants to arm each Zumwalt stealth destroyer with up to a dozen hypersonic missiles

• The Navy plans to arm Zumwalt destroyers with up to 12 hypersonic missiles, budget documents show.
• The Navy said in April that the Zumwalts will be the first warships to carry hypersonic missiles.
• The Navy has struggled to develop suitable armaments for this advanced class of warships.

The US Navy plans to put a dozen hypersonic missiles on each of its three Zumwalt-class destroyers, according to the latest budget documents.

The Department of the Navy included in its fiscal year 2022 budget proposal a request for funding to put the Conventional Prompt Strike (CPS) Weapon onto all three Zumwalt-class destroyers.

Doing so, the document says, will enable "a flexible, surface combatant-launched, long-range strike capability that leverages stealthy design to achieve precision strikes with low susceptibility to counter targeting."

To outfit the ships with CPS missiles, the Navy plans to modify the vessels and install a cold launch system "with the capacity to carry up to 12 all-up rounds per ship."

This piece of the Navy's $211.7 billion budget request, which was first reported by Defense Daily, offers a clearer picture of how the service's stealthy Zumwalt-class destroyers might fight in a potential future conflict.

The Navy originally envisioned using the stealth Zumwalt-class destroyers to fight from the littorals and support ground troops with fire from the two 155 mm guns of the Advanced Gun System.

The powerful gun system, the largest built for and fitted on a warship since World War II, could put 10 rounds a minute on targets up to 83 nautical miles away.

The Navy's plans for the destroyers were upended in 2016 - just a couple of weeks after the-first-in-class USS Zumwalt (DDG-1000) was commissioned - when reductions in the size of the class from nearly three dozen to just three resulted in a sharp increase in the cost of the ammunition for the main guns.

A single Long Range Land Attack Projectile was going to cost almost $1 million. Unable to afford the ammunition, the Navy was forced to shutdown procurement and rethink the armaments for the Zumwalt-class destroyers.

The Navy opted to change the destroyers' mission from land attack to surface warfare, aiming to transform them into stealthy ship-killers, but there were still questions about how to arm them.

The deputy chief of naval operations for warfare systems said in 2018 that the Navy had "determined that the best future for that ship is to get it out there with the capability that it has and separate out the Advanced Gun System, leaving everything else in place."

He further explained that the Zumwalt, the Navy's most technologically advanced ship, would "be a candidate for any advanced weapon system that we develop."

At one point in time, there was talk of arming the Zumwalt with the electromagnetic railgun the Navy spent years developing, but that weapon never really materialized. The Navy's newest budget request suggests that the service is no longer funding the development of this weapon, which was could fire hypervelocity projectiles that would strike like a meteor.

Although the Navy has struggled to work through the advanced weaponry problems, it has made progress on other armaments. USS Zumwalt was delivered to the Navy with a working combat system early last year.

The Zumwalt test-fired the 30 mm mark 46 MOD 2 Gun Weapon System, a remotely operated, high-velocity naval cannon for taking out small, high-speed surface threats, for the first time last May, and in October, the ship test-fired an SM-2 missile for the first time.

In April of this year, Chief of Naval Operations Adm. Mike Gilday revealed that the Zumwalt-class destroyers will be the service's first warfighting vessels to be armed with hypersonic missiles, specifically the Navy's CPS Weapon.

The CPS Weapon, which the Navy says will "enhance US conventional power projection through longer range, shorter time of flight, and higher survivability against enemy defenses," uses the Common Hypersonic Glide Body that the Army and Navy are working together to develop and successfully flight-tested in March 2020.

The hypersonic glide body is part of a hypersonic weapon that carries the warhead. Launched using a conventional rocket booster, the glide body eventually separates from the rocket and then continues on to the target.

After separation, the glide body is no longer able to accelerate, but it retains the ability to maneuver.

Hypersonic weapons can fly at speeds of at least Mach 5, but it is their maneuverability, unpredictability, and unusual flight path that makes them particularly dangerous. Existing air- and missile-defense systems are not well suited to countering this type of threat.

The Navy says that its CPS Weapon "will deliver a hypersonic conventional offensive strike capability through a depressed boost-glide trajectory to prosecute deep inland, time-critical, soft and medium-hardened targets in contested environments."

Because these weapons are difficult to defeat, hypersonic missiles have become a key area of strategic competition between the US and its rivals China and Russia.

Gilday said in April that the Navy expects to deliver this capability to the fleet by 2025. After the CPS hypersonic missile has been installed on the Zumwalt destroyers, the Navy will move on to the Virginia-class submarines.