The annual US–Japan “Iron Fist” amphibious exercise will run from 11 February to 9 March 2026, Japan’s Ground Self-Defense Force announced, in what both sides describe as a routine drill but which is notable for its size and scope. This year’s iteration is the fourth to be staged on Japanese soil since the exercise moved from California in 2023, and organisers say it will span 19 sites across Okinawa and adjacent waters—the widest geographic footprint in the exercise’s 21-year history.
Participating forces include roughly 800 US Marines, some 2,100 US Navy personnel and more than 2,000 Japan Self-Defense Force members drawn from the Marine-style Amphibious Rapid Deployment Brigade (the so-called “Waterborne Mobility Corps”) and the Japan Maritime Self-Defense Force. The US will deploy three large amphibious ships while Japan will contribute destroyers, transports and aviation assets such as V-22 Ospreys, CH-47 Chinooks and AH-64D attack helicopters. Japanese and US officials say the two-stage drill will focus first on joint command, ground manoeuvres, live fire, engineering and medical logistics, before adding surface combatants in a larger maritime phase.
The exercise comes against a backdrop of rapid change in the alliance’s command arrangements and Japan’s security posture. In 2022 Tokyo released a suite of defence documents and, in 2024, established a Joint Command with operational authority inside the Defence Ministry. The US contemporaneously upgraded its command in Japan to a joint headquarters, a pairing that alliance planners say shortens decision chains by enabling Tokyo-based commanders to coordinate with US forces in real time rather than routing orders through US Indo‑Pacific Command in Hawaii.
Political currents in both capitals sharpen the exercise’s significance. Prime Minister Sanae Takaichi, who took office in October 2025, has pressed Japan to spend more on defence and has publicly suggested that a Taiwan conflict that involved warships could constitute an existential threat to Japan—an assertion that raises the possibility of Japanese forces operating in or near the Taiwan Strait. In Washington, the return of Donald Trump has not removed rivalry with China from the strategic agenda; recent US defence documents still treat China as the principal long-term competitor, even as the administration rebalances focus toward the Western Hemisphere.
Taken together, the larger exercise, deeper operational integration and sharper political rhetoric point to a new normal: systematic training of US and Japanese forces for amphibious operations in Japan’s south‑west island chains. The drills are explicitly designed to improve rapid reaction and island-defence capabilities, tasks that were previously largely theoretical for Japan’s post‑war security posture but are now operational priorities as Tokyo builds out brigade-level amphibious forces.
That modernisation is consequential for regional stability. From the perspective of Beijing and many regional capitals, large-scale amphibious rehearsals on and around Okinawa are hard to separate from contingency planning for Taiwan or disputed island scenarios. From the alliance’s perspective, more realistic training and closer command ties improve deterrence and reduce the risk of slow, disconnected responses in a crisis. Yet the very realism that strengthens deterrent credibility also raises the risk of accidents, miscalculation and escalatory signalling in a densely contested maritime environment.
For neighbours and partners, the exercise is a reminder that the US–Japan alliance sits at the centre of Washington’s Indo‑Pacific strategy and that Tokyo is more willing than in decades past to field forces with expeditionary, offensive characteristics. The US has encouraged burden‑sharing and capability enhancement among allies; Japan under Takaichi has responded by accelerating its rearmament and by publicly embracing firmer security roles. The result is a stronger, more integrated two‑power force with the power to shape crises—but also the capacity to inflame them.
Regional governments will now face trade-offs between deterrence and de‑escalation. ASEAN capitals and others who prize status quo stability are likely to urge restraint and transparency, while Taipei will closely watch drill locations and force compositions for signals about potential Japanese involvement in Taiwan contingencies. Washington and Tokyo, for their part, will need to manage domestic legal and political constraints—particularly Tokyo’s still‑sensitive constitutional limits on the use of force—while making alliance operations credible.