Photo Information

A U.S. Marine Corps MV-22B Osprey with Marine Medium Tiltrotor Squadron 265 (Reinforced), 31st Marine Expeditionary Unit, and a Japanese Ground Self-Defense Force V-22 Osprey with the 107th Aviation Unit conduct a bilateral formation flight over Mount Fuji, Japan, Mar. 17, 2022. Bilateral flights build familiarity and interoperability between U.S. and Japanese aviation units. Maritime Defense Exercise Amphibious Ready Deployment Brigade is a bilateral exercise meant to increase interoperability and strengthen ties between U.S. and Japanese forces for the defense of Japan. (U.S. Marine Corps photo by Lance Cpl. Cesar Ronaldo Alarcon)

Photo by Lance Cpl. Cesar Alarcon

MDX-ARDB: Stronger Together

14 Mar 2022 | 31st Marine Expeditionary Unit

U.S. Marines from the 31st Marine Expeditionary Unit and members of the Japan Ground Self-Defense Force’s Amphibious Rapid Deployment Brigade began their first dedicated bilateral training exercise together, taking place at Numazu Beach, Japan, and Combined Arms Training Center Fuji, Japan.

The exercise known as the Maritime Defense Exercise-Amphibious Rapid Deployment Brigade began with a staff exercise that preceded the event. This event allowed 31st MEU and ARDB leadership to conduct detailed planning at the ARDB home station, Camp Ainoura, Japan.

“The 31st MEU and ARDB are two of the best trained and most prepared crisis response forces within the First Island chain,” said Col. Michael Nakonieczny, commanding officer of the 31st MEU.  “The main purpose of MDX-ARB is to reinforce our long standing relationship with the ARDB, deter competitor and adversary aggression, and highlight that the 31st MEU and ARDB are prepared to respond to any crisis, at any time, together.”

MDX-ARDB enables participants to work as dedicated partners in support of the U.S.-Japan security alliance while demonstrating evolutions such as an amphibious landing, combined arms trainings, and functional level training to hone key tactics and skills.
The exercise includes Marines and sailors from the 31st MEU, including participation from the U.S. Air Force 374th Airlift Wing and Naval Mobile Construction Battalion 3 Seabees. Japanese counterparts are provided by the 1st Amphibious Rapid Deployment Regiment of the ARDB. The ARDB is an amphibious unit of the JGSDF.

“We are committed to our enduring foundation and to building interoperability,” said Col. Masahi Hiraki, commander of the 1st Amphibious Rapid Deployment Regiment. “We are here to strengthen our ties. Bilateral trainings like MDX-ARDB conducted between the U.S. Marine Corps and ARDB demonstrate both countries’ devotion to their mutual partnership and dedication to peace and stability in the region.”

MDX-ARDB seeks to strengthen the defensive capabilities of the U.S.-Japan alliance in support of defending key maritime terrain. Combined bilateral activities such as bilateral command and control in a distributed environment allows the two countries to mutually learn and grow from one another.

All U.S. personnel participating in MDX-ARDB are abiding by all USFJ-mandated COVID-19 prevention procedures in order to keep local Japanese communities and the combined military force safe and healthy. All U.S. participants are fully-vaccinated.

Bilateral training exercises like MDX-ARDB allow the Japan Self-Defense Force and forward-deployed U.S. Marine Corps forces to focus on the development and refinement of critical bilateral planning, coordination, and interoperability efforts.

“We are prepared for challenges that we may face together,” said Lt. Col. Brendan Neagle, operations officer of the 31st MEU. “Together, we are strong and capable and I look forward to planning future iterations of this exercise.”

MDX-ARDB reinforces that the U.S. Marine Corps and the ARDB can operate in non-traditional environments and thrive. Continued bilateral trainings like MDX-ARDB showcase the continued devotion of U.S. and Japanese forces to maintain international norms and their dedication to defending a free and open Indo-Pacific region.

Photos, videos, and news stories about MDX-ARDB are available at 

Photos, videos, and news stories about the 31st MEU are available at