Recently, Naval News contacted the U.S. Special Operations Command (USSOCOM) for insights into the role and value of the U.S. Navy’s Expeditionary Sea Bases, specifically designed for special operations and expeditionary warfare.

Supporting a Wide Variety of Missions

Expeditionary Sea Base vessels (ESBs) are multifaceted platforms that enable special operations forces to undertake a wide variety of missions, including mine countermeasures, special operations, rotorcraft maintenance, refueling, and more.

Adapted from the design of the civilian Alaska-class oil tankers, these ships boast a cruising speed exceeding 15 knots, can cover 9,500 nautical miles at this pace, and displace 90,000 tons. They measure 239.3 meters in length and have a beam of 50 meters. Though they lack armor and automated close-in weapons systems, they are defended by manually operated .50 caliber and 7.62mm M240B machine guns.

The ESBs are equipped with extensive facilities, including storage for fuel and equipment, weapon and explosive ordnance disposal magazines, mission planning spaces, and support features for health, fitness, and nourishment for a crew of 34 and a military detachment of 250. Their flight decks accommodate up to four rotorcraft, with additional space for two in the hangar, catering specifically to helicopters and tilt rotors.

Four in Service, Two Under Construction

As of early 2024, the fleet includes six ESBs, four already in service and two more under construction. These vessels are heralded for their versatility and cost-effectiveness, which allow them to undertake a wide range of missions in various threat environments.

Sailors prepare to launch a rigid-hull inflatable boat (RHIB) aboard expeditionary sea base USS Miguel Keith (ESB 5), Aug. 15. Miguel Keith is underway conducting routine operations in U.S. 3rd Fleet. U.S. Navy photo by Mass Communication Specialist 2nd Class Jacob D. Bergh

USSOCOM highlighted the ESBs as a crucial asset in enhancing the capabilities of Special Operations Forces, providing them with a flexible global presence. However, they also noted that ESBs, while valuable, can only fulfill some Afloat Forward Staging Base (AFSB) roles independently and may require additional equipment based on the mission’s needs. Their primary use lies in offering extra deck space and flexibility for operations that exceed the capacity of other naval or SOCOM-specific maritime support vessels.

Before the introduction of ESBs, USSOCOM relied on the Navy’s amphibious ships for such operations. The USS Ponce (LPD 15), which was decommissioned in 2017, served as a precursor to the current ESB design, emphasizing the evolution and increasing significance of these vessels in U.S. naval operations.