The US Navy Is Upgrading Its Destroyer Deck Guns With A Versatile New Defense System

The United States Navy has a large fleet of ships, maintaining 74 Arleigh Burke-class destroyers deployed across the world. Destroyers of this class, which include Flights I, II, IIA, and III, measure 509 feet long with a 66-foot beam, and they displace 9,300 tons of seawater. They're typically crewed by a between 303 and 323 personnel, and they're outfitted with a variety of weapons systems. They feature the Aegis Combat System that centers around the Mk. 41 Vertical Launching System, which is capable of firing off a variety of missiles.

They also feature a 5-inch Mk 45 62 caliber lightweight gun, two 25mm Mk. 38 machine guns, and .50 caliber machine guns. Additionally, the Arleigh Burke-class come equipped with the Phalanx 30mm Close-In Weapons System (CIWS), which is used for defense against drones, small nearby surface vessels, and can shoot down incoming missiles and indirect fire munitions. One ship, the USS Mustin (DDG-89), was outfitted with an entirely new type of point defense system, the Mk. 38 Mod 4, and its versatility and lethality make it ideal for future destroyers.

The Navy has already ordered an additional 22 Mk. 38 Mod 4 weapons systems to be installed on other destroyers, and it's likely that more will be outfitted on additional vessels. What makes it special is that the Mk. 38 Mod 4 pairs a 30mm cannon with a .50 caliber machine gun, and it's all operated remotely as a defensive system targeting the same types of threats as the Phalanx CIWS. Despite this, the Navy isn't ready to retire the Phalanx just yet, as it's boosted several contracts to keep the program running until at least 2029.

The Mk. 38 Mod 4 is produced by MSI-Defence Systems, and while only one set has been installed aboard a modernized Arleigh Burke-class destroyer as of this writing, it already looks like a game-changer. It's equipped with a Mk. 44S 30 mm cannon coaxially mounted with the 12.7mm M3HB .50 caliber heavy machine gun. By piggybacking the two weapons, the Mk. 38 Mod 4 offers increased engagement capabilities. The system is optimized to engage Fast Inshore Attack Craft (FIAC), like the boats Iran uses to target large warships. It's also ideal for targeting Uncrewed Aerial Systems (UASs).

It's operated via the onboard Combat Management System or Electro-Optical Fire Control System using the remote independent Electro-Optical Sight System. What all of that means is that nobody needs to interact with the Mk. 38 Mod 4 to use it, as once it's loaded with ammunition, it can be operated remotely, reducing the danger to anyone on the deck. The system is modular and accurate at extended ranges using the full range of NATO-standard ammunition.

It can fire air-burst munitions, which are ideal for striking fast-moving targets, ensuring it's as accurate and deadly as possible. Everything about the Mk. 38 Mod 4 improves upon prior versions of the system, offering enhanced lethality and survivability for itself and whatever ship it's installed upon. On October 7, 2026, the Navy ordered an additional 22 Mk. 38 Mod 4 systems via a three-year $197 million contract, and it's likely that they'll be installed on other Arleigh Burke-class destroyers in the coming years.