The Zumwalt-class stealth destroyers are considered the most advanced surface warships in the world, equipped with innovative naval technology.

Named after Adm. Elmo R. Zumwalt Jr., the youngest chief of naval operations in US history, the lead ship USS Zumwalt is the largest destroyer in the world at 610 feet long. It can house a crew of nearly 200 sailors and accommodate one MH-60R Seahawk helicopter in its hangar.

General Dynamics Bath Iron Works and Huntington Ingalls Industries were behind the design and construction of the three stealth destroyers.

The warships feature an all-electric propulsion system and a composite deckhouse covered with radar-absorbing material to hide their sensors and communication systems. But the US Navy has struggled to arm them.

Due to the ship's manufacturing issues and soaring costs, the Navy reduced the Zumwalt class's overall size from 32 ships to just three: the Zumwalt, USS Michael Monsoor, and the future USS Lyndon B. Johnson, which is expected to commission after its combat systems are fully installed and activated.

The stealth destroyers were armed with two 155 mm deck guns for shore bombardment, but ballooning manufacturing costs made the ammunition for the guns ridiculously expensive.

The Navy halted the ammo procurement in 2016, the same year the Zumwalt was commissioned, and publicly announced in 2018 that it was scrapping the now-useless main deck guns for a new weapon system.

In 2021, then-Chief of Naval Operations Adm. Mike Gilday said the stealth destroyers would be the first Navy warships to be armed with hypersonic missiles instead of its Block V Virginia-class submarines, saying that it would be an "important move" toward turning the surface ships into strike platforms.

The Navy said the first-in-class stealth destroyer's "upgrades will ensure Zumwalt remains one of the most technologically advanced and lethal ships in the US Navy."

Photos showed the Zumwalt's main deck gun mounts were removed. The cannons will be replaced with four all-up round canisters containing three hypersonic missiles each. These come in addition to its conventional missile arsenal of 80 vertical launch cells.

The US military is working on hypersonic weapons across all branches. The Zumwalts will be armed with the Conventional Prompt Strike (CPS) system, the Navy's joint hypersonic weapons program with the Army and US Strategic Command.

Described by STRATCOM as "a strong deterrence message to our adversaries," the "highly lethal platform" would launch like a ballistic missile but instead uses a two-stage solid-fueled rocket booster to get the projectile to travel at speeds faster than Mach 5 speed — nearly 4,000 mph. The booster allows the missile to change trajectory at these speeds, unlike a ballistic missile, and combined with its lower altitude flight complicates efforts to intercept it.

The weapon system features an all-up round (AUR) missile and a separate payload modular adapter, which the Navy is testing along with the missile and eject system.

"It's not like any other type of missile," Vice Adm. Johnny Wolfe, the Navy's director of strategic programs, told reporters at the Naval Submarine League's annual symposium last month. "You don't light this thing off inside."

The CPS system failed its first test in June 2022, as well as subsequent flight tests in March and September 2023. The first successful test was completed this summer.

"The testing that we need to do to get to the final integration of Zumwalt, that's irrespective of where the Zumwalt's at, whether it's in the water," Wolfe added.

In addition to the CPS system, the Navy is also developing a hypersonic air-launched anti-ship missile expected to be compatible with the F/A-18 Super Hornet fighter jet. However, few details about the $178.6 million program have been released to the public.

Developed to provide off-shore precision fire support from a distance, the Zumwalt-class stealth destroyers were armed with a pair of Advanced Gun System (AGS) mounts to fire naval artillery from up to 100 nautical miles away — in what would've been the US Navy's longest-range shell in use.

However, after the Navy reduced the size of its Zumwalt fleet, manufacturing costs for the Long-Range Land-Attack Projectile-guided shells skyrocketed to about $800,000 to $1 million per round — about the same price as a cruise missile.

The rocket-assisted projectiles also fell short of the intended range, prompting the sea service to cancel production of the munitions, rendering the pair of high-velocity cannons useless.

Before announcing the new hypersonic weapon, the Navy floated other weapon systems to replace the failed gun mounts, including an electromagnetic railgun or futuristic laser weapons.

In recent years, US adversaries like Russia and China have been developing hypersonic weapons, adding pressure on the Pentagon to prioritize its own hypersonic development efforts.

China has "the world's leading hypersonic arsenal," and Russia has already deployed two of its three hypersonic weapon systems in Ukraine, according to congressional testimony from Jeffrey McCormick, senior intelligence analyst at the National Air and Space Intelligence Center.

The US, however, has yet to field a single hypersonic weapon amid ongoing development and integration challenges across the military, including the Zumwalt-class artillery upgrade.

Research and development for the destroyer cost about $22.4 billion, and General Dynamics spent another $40 million just to construct a shipyard facility large enough to accommodate the giant hull segments.

Each ship cost an average of $7.5 billion — more expensive than the Navy's Nimitz-class aircraft carriers.

Even with all of their costly innovations, the Zumwalt-class vessels continued to be plagued by equipment problems and constantly needed repairs.

Last year, the Navy awarded Huntington Ingalls Industries with a $154.8 million contract to integrate the hypersonic weapon system aboard USS Zumwalt. The Congressional Budget Office also estimated that it would cost nearly $18 billion to buy and maintain 300 of the hypersonic boost-glide missiles for the next 20 years.

As the expenses of fielding US-developed hypersonic weapons pile up, some military analysts say the costs outweigh the benefits.

"This particular missile costs more than a dozen tanks," Loren Thompson, a defense analyst at the DC-based think tank Lexington Institute, told the Associated Press. "All it gets you is a precise non-nuclear explosion, someplace far, far away."

"Is it really worth the money?" Thompson continued. "The answer is, most of the time, the missile costs much more than any target you can destroy with it."

While conventional missiles may cost less, long-range hypersonic weapons increase the chances of striking the targets of adversaries protected by advanced air defense systems like those of China and Russia.

"The adversary has them," retired Navy Rear Adm. Ray Spicer, CEO of the US Naval Institute, told the AP. "We never want to be outdone."

Bryan Clark, a defense analyst at the Hudson Institute, told the AP that while the US stealth destroyers were "a costly blunder," the Navy could "take victory from the jaws of defeat here and get some utility out of them by making them into a hypersonic platform."

The jury is still out on whether the Zumwalt hypersonic upgrades are worth the hefty price tag, but it would at the very least give the stealth destroyers a purpose.

"Zumwalt gave us an opportunity to get [hypersonics] out faster," Gilday told USNI News in 2022," and to be honest with you, I need a solid mission for Zumwalt."