On a tropical island within the First Island Chain, planners from the U.S. Marine Corps and the Japan Ground Self Defense Force are deeply engrossed in their work, studying maps under tan weathered tents. Their focus is on wargaming enemy actions within their battlespace, while attentive interpreters in their native military uniforms mediate technical discussions, dictating their nation's part in the Stand-in Force.

At the same time, U.S. Marines execute a swift and precise deployment from an MV-22B Osprey over the island of Ie Shima. They rapidly fast rope to the ground and seek cover among the mangrove trees. Assessing their surroundings, they strategize their approach to the unpredictable river lying ahead, which poses as a formidable obstacle on their way to the next objective. These Marines belong to the highly capable III Marine Expeditionary Force.

On July 6, 2023, a host of Marines from the 3rd Marine Division assemble at Kadena Air Base, don their combat loads, and anticipate the powerful aircraft’s transport of them within a matter of hours to an austere destination. This mission is part of the Alert Contingency Marine Air-Ground Task Force Exercise, testing the Marines' ability to immediately provide unwavering support to allies and partners during regional emergencies, be it natural disasters or hostile actions.

As part of the Stand-in Force, the Marines and Sailors of III MEF undergo rigorous, comprehensive training. Their preparation focuses on thriving in remote locations, maneuvering with a low signature, and responding effectively if detected. This training also includes reducing their logistical dependence, as they learn to subsist independently by generating their own power, water, food, and fuel from the environment.

III MEF collaborates closely with the U.S. Navy’s 7th Fleet, working together to conduct sea control operations in isolated maritime terrain. Their synergy ensures that they stand strong as a Stand-in Force, ready to face any challenge that may arise. Every occupation within III MEF diligently shifts its focus to training in dynamic scenarios, fostering adaptability and versatility.

U.S. Marine Corps Lt. Col. George Rawson, the current operations officer for 3rd Marine Division, emphasizes, "As the nation’s Stand-in Force in the Indo-Pacific Command, III MEF uses ACMEX to display the utility of the ACM as a general-purpose response force that provides the combatant commander flexible options across the full range of military operations."

III MEF functions as a well-integrated and cohesive team, with subordinate units fulfilling various critical functions. Whether they are preparing an AGM-84D Harpoon Missile, conducting aerial refueling, or exchanging expertise with allied forces, every member plays a pivotal role in supporting the main body's mission.

Units from 3rd Marine Logistics Group continuously refine their systems, ensuring that III MEF possesses the necessary speed and efficiency in execution. During the Combined Distribution Exercise in June 2023, 3rd Landing Support Battalion showcased their capabilities, including water production, aerial medical evacuation drills, and resource delivery through the Joint Precision Airdrop System. This exercise demonstrated III MEF’s joint and bilateral operability, as logistics units from Republic of Korea forces, the U.S. Air Force, U.S. Army, and U.S. Navy joined forces with 3rd Landing Support Battalion.

Simultaneously, III MEF conducts a series of training events with allies and joint force partners across Japan, the Philippines, and Australia. These events actively build interoperability, enhancing the readiness of forces and making notable contributions to regional security and stability in the Indo-Pacific.

Helicopter crews from the 1st Marine Aircraft Wing participated in Marine Aviation Support Activity (MASA) 23 from July 6 to July 21. During this exercise, they train extensively with squadrons from various U.S. Marine Corps units, the U.S. Air Force, and the Armed Forces of the Philippines. The training encompasses a wide array of activities, including bilateral air assaults, aerial sniping, fuel delivery in the air, jungle patrolling, and fast rope helicopter insertion training. During their training operations, these Marines reside on the ground in the teeming jungle, alongside their comrades from III MEF and the Filipino Marines, immersing themselves in the true essence of the Stand-in Force in the littoral environment.

"We are ready to go fight," says Lt. Col. Thomas Duff, commanding officer of Marine Light Attack Helicopter Squadron 169 (HMLA-169). "MASA gives us the ability to strengthen relationships, hone our warfighting skills, and practice in a distributed fashion in the [Expeditionary Advanced Base Operations] context. We will be here in the first island chain, fighting in the seams, because that’s where we thrive."

Across Okinawa's remote maritime terrain, the III MEF Information Group deploys low-profile, highly mobile sensor teams to help identify adversary intentions, adding an extra layer of preparedness and situational awareness to the Stand-in Force. A member of a sensing team, 23-year-old U.S. Marine Corps Sgt. John Philips, a native of Gaffney, S.C., and a radio operator with 5th ANGLICO, III MEF Information Group, created a field expedient radio antenna using raw materials and a protein shaker bottle, highlighting the resourcefulness inherent in the Stand-in Force.

Col. Rich Martin, the III MIG commanding officer, highlights, "One of the hallmarks of a viable Stand-in Force is the ability to persist in forward locations and operate effectively when competition shifts into crisis, being able to provide reliable battlespace awareness and deliver effects that frustrate the adversary's ability to gain an advantage—that's how information is playing a key role for the MEF and the joint force."

The synchronized aggregate of III MEF forms an agile and highly capable Stand-in Force, ready to respond swiftly to any crisis or contingency. While this capability is not intended for long-term solutions, the combined strength of III MEF's functions serves as the most efficient tool for rapid response. Whether working from rugged planning tents or tactical positions, III MEF effectively sets the conditions for follow-on action, ensuring their readiness for any eventuality.

The Marine Corps remains prepared for a full-scale conflict, and as part of the Stand-in Force in the Indo-Pacific, it contributes to the success of joint and combined forces in the region. Packing lighter than before, III MEF, flanked by its allies and partners, stands sharper and more formidable than ever.