The biennial Rim of the Pacific Exercise, or RIMPAC, is one of the most important military exercises in the Indo-Pacific. This year’s theme, “Partners: Integrated and Prepared,” highlights the central purpose of the U.S.-led exercise: strengthening collective defense and multinational operational coordination across the region. 

More specifically, RIMPAC is designed to integrate the operational mechanisms, command procedures, and military systems of the United States and its allies and partners. RIMPAC 2026, which started on June 24 and will conclude on July 31, reflects several important strategic concepts.

Strengthening Undersea Warfare

One of the most important features of this year’s RIMPAC is the emphasis on submarines and anti-submarine warfare aircraft. This reflects growing concern over the expanding carrier and undersea capabilities of the People’s Liberation Army Navy (PLAN).

Since the previous RIMPAC in 2024, China’s aircraft carrier development and operations have drawn increasing international attention. In addition to conducting more frequent maritime exercises in the Western Pacific, China has also introduced new carrier-related aircraft, including newer variants of the J-15 and the J-35. The Liaoning has carried out repeated takeoff and landing training in the East China Sea and the Western Pacific. In 2025, China’s two-carrier operations beyond the First Island Chain and deeper into the Pacific further heightened regional concern over the PLAN’s carrier capabilities. These developments naturally make China’s carrier strike groups a major focus as participating countries seek to integrate and coordinate their operational capabilities during RIMPAC.

At present, the deployment of land-based anti-ship missiles remains an important tactic for the United States and its allies along the First Island Chain. This “using land to control the sea” approach is a practical way to counter the PLAN. However, when it comes to countering Chinese aircraft carriers, undersea attack remains one of the most effective options. Compared with engaging the PLAN through surface anti-ship or air-defense operations, submarines can provide a more survivable and effective means of threatening carrier strike groups.

How to integrate undersea forces for operations against PLAN carrier formations will therefore be one of the key areas of training for the United States and its partners in this year’s RIMPAC. Five submarines are reportedly taking part in RIMPAC 2026, compared to just three in RIMPAC 2024.

Learning From Recent U.S. Combat Experience

Another important aspect of this year’s exercise is the opportunity for participating countries to learn from recent U.S. operational experience, particularly in air defense, counter-drone operations, and responses to unmanned surface vessels in the Middle East.

For the 30 participating countries, RIMPAC is not only an opportunity to conduct joint exercises with the U.S. military and become familiar with one another’s doctrines and new equipment. It is also a platform for system integration and combined personnel training. This is one of the main reasons why countries continue to attach importance to participation in RIMPAC.

In recent years, however, U.S. forces have also accumulated valuable real-world experience in the Middle East. Recent operations have shown that traditional missile defense systems are facing new challenges. The most pressing aerial threat today is no longer limited to aircraft or missiles, but increasingly comes from large numbers of low-cost unmanned systems. This has forced air-defense systems to adapt to a changing threat environment.

The various drones and unmanned surface vessels encountered by U.S. forces in the Middle East provide lessons that are extremely valuable for other countries. These are precisely the kinds of battlefield experiences that participating states will seek to absorb from the United States during RIMPAC 2026.

The Significance of SINKEX

RIMPAC also included a multinational live-fire sinking exercise, known as SINKEX. This year’s target vessels reportedly include the decommissioned amphibious assault ship Peleliu and the former Aegis cruiser Mobile Bay. Participating forces will conduct live-fire attacks from land, sea, and air, testing multinational strike coordination, weapons integration, and command-and-control capabilities. Before launching the strikes, participating countries will also have the opportunity to test maritime replenishment and joint logistical coordination.

The purpose of SINKEX is not only to allow participating personnel to experience the impact of live-fire operations. It also provides an opportunity to evaluate the effects of different weapons against real naval targets. The U.S. military can assess how many munitions are needed, where they should strike, and what kinds of damage are required to disable or sink different types of vessels.

This year’s target ships are especially noteworthy. A large amphibious assault ship and a 10,000-ton-class cruiser resemble, in general operational terms, the types of vessels the PLAN is now developing and deploying, including the Type 075 and Type 076 amphibious assault ships and the Type 055 large destroyer. In this sense, SINKEX is not only a weapons test. It is also a rehearsal for the kinds of maritime targets that allied forces may encounter in a future conflict.

Implications for Taiwan

Although Taiwan cannot send its military forces to participate in RIMPAC 2026, the exercise still deserves close attention. The core value of RIMPAC lies not only in the deployment of ships, aircraft, and troops, but also in the operation of command systems and the evolution of tactics. Whether Taiwan participates directly with forces is therefore not the only issue.

Taiwan’s own defense posture is centered primarily on island defense, which differs from RIMPAC’s emphasis on large-scale maritime and air operations across the open ocean. Given this difference in strategic objectives, Taiwan should pay particular attention to how participating countries integrate command systems, connect platforms, and coordinate operations across multiple domains.

Over the years, RIMPAC has provided the United States and its partners with a venue to test new operational concepts and tactics. These tactical innovations are worth studying closely. Taiwan may not face the same operational environment, and some aspects of large-scale multinational maritime operations may not directly apply to Taiwan’s defense needs. Nevertheless, by observing RIMPAC, Taiwan can better understand how emerging technologies are reshaping military operations.

For Taiwan, the most important lesson is not simply how many ships or aircraft participate in the exercise. Rather, it is how modern militaries integrate sensors, platforms, weapons, command networks, and allied forces into a coherent operational system. In this sense, RIMPAC remains an important window into the future of Indo-Pacific military cooperation – and a valuable reference point for Taiwan as it seeks to keep its own defense thinking up to date.