The U.S. Navy has launched a new multi-year program to sustain, upgrade, and overhaul the Phalanx Close-In Weapon System (CIWS) across its surface fleet. This initiative is intended to ensure that the service’s last line of ship defense remains effective against increasingly complex missile and drone threats.
Planning documents released in September 2025 outline a structured, multi-year approach for the MK-15 Phalanx system, tying together production support, modernization, and overhauls. By consolidating sustainment actions, the Navy aims to guarantee consistent availability of the CIWS on surface combatants well into the next decade.
Phalanx operates as the fleet’s ultimate safeguard when other layers of defense have been exhausted. The system integrates a 20 mm M61 Gatling gun with Ku-band radar and an electro-optical turret for tracking, identification, and engagement. With a firing rate of up to 4,500 rounds per minute and a magazine capacity of roughly 1,550 rounds, its employment requires tight fire discipline. Crews typically engage in controlled bursts, evaluate impact, and reengage as needed, making ammunition management an integral part of fire control.
The current standard across the fleet is the Block 1B Baseline 2. This variant incorporates surface-targeting capability and stabilized infrared imaging, improving performance against low-flying drones, small craft, and targets masked by sea clutter. Armor-piercing sabot rounds disrupt missile aerodynamics and fracture airframes, buying critical distance to avoid impact. Effective performance, however, depends heavily on the speed and accuracy of the sensor-to-computer loop, as engagement opportunities are measured in seconds.
