Iron Fist 26 Steps into the Southwest Outdoor Terrain, Japan-U.S. Amphibious Operations Enter a New Phase

In Iron Fist 26, which began this month, a spokesperson from the Japan Ground Self-Defense Force used a specific expression: "Southwest region outdoor." This term was not found in exercise notifications until last year. It is clearly different in quality from the conventional exercise announcements that listed well-maintained facility names like Camp Hansen and Kin Red Beach.

Scale and Deployment of the 20th Iron Fist

Iron Fist 26 is an annual bilateral amphibious exercise between Japan and the U.S. conducted from February to March 9. This year marks the 20th iteration, and the scale has significantly expanded. Approximately 2,000 personnel from the Japan Ground Self-Defense Force, about 800 from the U.S. Marine Corps, and around 2,100 from the U.S. Navy are participating, totaling about 5,000 personnel. The exercise will take place at 19 locations within the Southwest Islands, an increase of three locations from last year. Additionally, this year, the Japan Maritime Self-Defense Force's amphibious units are also involved. The main units are the U.S. 3rd Marine Expeditionary Brigade and the Japan Ground Self-Defense Force's Amphibious Rapid Deployment Brigade, with core bases at Camp Hansen, Kin Blue Beach, and Red Beach in Okinawa.

What characterizes the exercise is not just the scale of numbers but the engagement with "outdoor terrain." Many islands in the Southwest Islands have extremely limited port facilities, and well-maintained beaches are rather exceptional. Outdoor deployment training means actually walking the dotted lines on a map with one's own feet. Beaches without piers, landing sites without pavement, ridgelines without radio relay stations. Operations in such environments present a significant gap between recording "completed" in the training plan and developing units that can actually operate.

The Strategic Context Behind the Term "Southwest"

During his visit to Okinawa on January 7 this year, Defense Minister Koizumi stated, "Strengthening deterrence and response capabilities in the Southwest region is an urgent issue." This statement suggests that the Ministry of Defense is beginning to treat island defense, with the so-called "Taiwan contingency" in mind, not as a mid- to long-term issue but as an immediate practical matter.

The Chinese response is also noteworthy. Chinese military-affiliated media labeled Iron Fist 26 as "interference in the Taiwan issue," while claiming that the U.S. military's presence around the Ryukyu Islands is diminishing. This is partly a form of external propaganda, but it may also reflect awareness of the ongoing "DPRI issue" in the U.S.—the plan to relocate about 5,000 Marines from Okinawa to Guam and elsewhere. If the DPRI proceeds as planned, the realistic deterrent effect of exercises like Iron Fist will decrease year by year.

"Improvement of operational capabilities in the outdoor areas of the Southwest region"—this expression indicates that the exercise is transitioning from "show training" to "usable training."

As a former member of the Maritime Self-Defense Force, I would add that the effectiveness of amphibious operations is not determined solely by the proficiency of ground forces. The maintenance of maritime supply lines connecting the islands and the sustainability of operations within the range of enemy anti-ship missiles are at the core of the issue. While the participation of the Maritime Self-Defense Force in Iron Fist 26 is commendable, the publicly available information does not clarify "at what stage of intervention is being assumed" in the training scenario.

Overlooked Risks

As the media focuses on Taiwan and China, one variable is being overlooked: North Korea.

The Workers' Party of Korea is expected to hold its 9th Party Congress within a few weeks, and Kim Jong-un has stated that he will "clarify the next phase plan for nuclear capabilities." According to analysis from the Stimson Center, North Korea may be advancing the practical deployment of the solid-fuel ICBM "Hwasong-20" by 2026. Historically, ballistic missile test launches have often coincided with party congresses.

The problem is that the peak of Iron Fist 26 in early March may coincide with this party congress. If North Korea were to launch a ballistic missile, the Japan-U.S. command structure would have to simultaneously address two entirely different situations: the amphibious exercise in the Southwest Islands and ballistic missile defense (BMD) response. Does the current Japan-U.S. joint response plan adequately incorporate scenarios where the threats from China and North Korea occur simultaneously? I have not found the answer in official documents.