31st MEU Supports Anti-Submarine Warfare Operation in Indo-Pacific

12 August 2025

From Capt. Robert DeRonda, 31st Marine Expeditionary Unit

CAMP HANSEN, Japan — On Aug. 8, 2025, Marine Medium Tiltrotor Squadron 265 (Reinforced), 31st Marine Expeditionary Unit, supported an operational anti-submarine warfare mission utilizing the MV-22B Osprey teamed with two Navy MH-60R Sea Hawk helicopters to distribute sonobuoys.

Download

A U.S. Marine Corps MV-22B Osprey assigned to Marine Medium Tiltrotor Squadron (VMM) 265 (Rein.), 31st Marine Expeditionary Unit, supports anti-submarine warfare training, in the Philippine Sea, Aug. 8, 2025. The Marines conducted the training utilizing buoys to detect underwater acoustics for ships and submarines in order to increase U.S. naval forces capabilities to detect and deter in the undersea domain. The 31st MEU is operating aboard ships of the USS America Amphibious Ready Group in the 7th Fleet area of operations, the U.S. Navy’s largest forward-deployed numbered fleet, and routinely interacts and operates with allies and partners in preserving a free and open Indo-Pacific region. (U.S. Marine Corps photo by Cpl. Alora Finigan)

U.S. Marine Corps Cpl. Tristan Courtney, a crew chief with Marine Medium Tiltrotor Squadron (VMM) 265 (Rein.), 31st Marine Expeditionary Unit, deploys buoys during anti-submarine warfare training, in the Philippine Sea, Aug. 8, 2025. The Marines conducted the training utilizing buoys to detect underwater acoustics for ships and submarines in order to increase U.S. naval forces capabilities to detect and deter in the undersea domain. The 31st MEU is operating aboard ships of the USS America Amphibious Ready Group in the 7th Fleet area of operations, the U.S. Navy’s largest forward-deployed numbered fleet, and routinely interacts and operates with allies and partners in preserving a free and open Indo-Pacific region. Courtney is a native of Ohio. (U.S. Marine Corps photo by Cpl. Alora Finigan)

This iteration of anti-submarine operations represents the first time a forward-deployed MV-22B assigned to the 31st MEU has operated in an ASW role within the Indo-Pacific theater, significantly enhancing the 31st MEU’s capabilities and contributing to regional maritime security.

“The Marine Corps has spent the past five years re tooling to fight in the Pacific and the submarine threat can’t be ignored. The MV-22B complements the Navy’s capabilities so well that it’s hard to believe this wasn’t thought of sooner” said Colonel Niedziocha, Commanding Officer, 31st MEU. “We’ve validated the utility of both amphibious warships and littoral forces, demonstrating the ability to fight as the landward component of the fleet.”

The integration of the MV-22B into ASW operations expands the MEU’s ability to detect, track, and deter potential adversaries operating in the maritime domain. This capability leverages the unique range, speed, and carrying capacity capabilities of the MV-22B with the deployment of advanced sensors and integration with U.S. Navy capabilities, allowing for rapid response and persistent surveillance.

This operation demonstrated the close relationship between the 31st Marine Expeditionary Unit and U.S. Navy counterparts. Seamless integration and interoperability with the George Washington Carrier Strike Group and the America Expeditionary Strike Group highlighted the strength of combined naval forces. This development underscores the Marine Corps’ commitment to naval integration and the provision of a versatile, rapidly deployable force capable of addressing a wide range of contingencies.

The 31st MEU is operating aboard ships of the America Expeditionary Strike Group in the 7th Fleet area of operations, the U.S. Navy's largest forward-deployed numbered fleet which routinely interacts and operates with allies and partners in preserving a free and open Indo-Pacific region.

Photo and video packages, including B-roll, will be released by the 31st Marine Expeditionary Unit for media use. Content can be found at https://www.dvidshub.net/unit/31MEU.