US and Australian Navies Conduct High-Stakes Joint Operation in South China Sea Amid Rising Tensions – Sept 2025

The U.S. and Australian navies conducted a joint operation in the South China Sea on September 15–16, 2025, to enhance military integration, assert freedom of navigation, and deter coercive maritime claims—underscoring a deepening alliance amid rising regional tensions.

 The joint naval operation conducted between the United States Navy and the Royal Australian Navy in the South China Sea on September 15 and 16, 2025, was a deliberate and strategically significant event. It was not a media stunt, not a symbolic parade, and not a reaction to any single incident—it was a continuation of a longstanding policy and operational pattern designed to assert presence, maintain readiness, and deepen alliance-level military integration between two of the most capable maritime forces in the Indo-Pacific.

The USS Dewey, an Arleigh Burke-class guided-missile destroyer, represents one of the most versatile and technologically advanced surface warships in the U.S. Navy. As a Flight IIA variant, it is armed with a 96-cell Mk 41 Vertical Launch System, carrying a flexible mix of surface-to-air missiles (SM-2, SM-6), anti-submarine rockets (VL-ASROC), and land-attack Tomahawk cruise missiles. Its SPY-1D(V) radar system feeds into the Aegis Combat System, which allows the ship to track, classify, and engage a multitude of aerial threats across a wide battlespace. Its configuration enables it to perform as a central node in fleet air defense, anti-submarine warfare, and power projection.

Dewey also carries two MH-60R Seahawks, helicopters capable of detecting and prosecuting submarines beyond the ship’s sonar horizon. These aircraft can deploy sonobuoys, fire torpedoes, and coordinate with surface and air units, giving the Dewey eyes and ears in the deep. Importantly, this capability is not only used for combat, but also for strategic deterrence—any adversary has to calculate against the unknown location of these helicopters and the threat they pose.

HMAS Ballarat, although smaller in displacement and armament, plays an equally critical role in this partnership. It is an Anzac-class frigate modified extensively under Australia’s Anti-Ship Missile Defence (ASMD) upgrade program. This modernization equipped the ship with CEAFAR active phased array radar, CEAMOUNT illuminators, and a digital combat management system that dramatically improved its ability to detect, track, and respond to high-speed, complex aerial threats. It is equipped with the Evolved Sea Sparrow Missile (ESSM), a highly maneuverable, radar-guided interceptor capable of defeating incoming anti-ship missiles. Though it carries fewer missiles than a U.S. destroyer, its ability to rapidly refresh tracks and engage threats in close-in layers makes it a formidable defensive partner in a distributed task group.

During the two-day operation, Dewey and Ballarat worked in tandem to rehearse coordinated naval operations under realistic conditions. They maintained tight formation in open sea—an evolution that may seem simple but requires precision, especially in areas where unplanned contacts, weather, and unpredictable sea states can create risks of collision or interference. Such drills sharpen the crews’ ability to maintain constant positional awareness, maneuver with confidence, and execute battle formations rapidly when needed.

The simulated fire exercises served a crucial purpose. In today’s fast-paced combat environment, the time between threat detection and weapon launch is often measured in seconds. These rehearsals test how fast and how accurately the ships can go from identifying a potential threat to executing a coordinated response. It's during these drills that crews walk through rules of engagement, weapons selection, sensor fusion, and target confirmation—without the consequences of real combat. Mistakes in simulation can be corrected. In combat, hesitation or confusion could lead to a failed defense or even the loss of a ship.

An important part of the training was communications. Even among close allies, there are subtle differences in doctrine, terminology, and signal procedures. Training ensures that both navies speak a common tactical language and can share critical data in real time—whether that means voice comms, encrypted chat protocols, or sensor information relayed via secure datalinks. In modern naval warfare, information dominance is often more decisive than firepower. The ability to push tracks from one ship’s radar to another ship’s weapon system allows for distributed lethality—where the whole task force becomes a sensor-shooter network rather than independent platforms acting alone.

This entire operation occurred in international waters, consistent with international maritime law. No nation has the right to restrict freedom of navigation in these areas, and both the United States and Australia are committed to upholding that principle not only through words, but through action. These are not high-profile, headline-grabbing deployments; they are regular, persistent, and professional demonstrations that allied navies will not allow the erosion of maritime freedoms through intimidation or the gradual normalization of illegal claims.

The broader strategic backdrop is also worth examining. China continues to assert expansive maritime claims in the South China Sea, building artificial islands and placing military systems on them to extend its reach and deter other nations from operating freely. The presence of U.S. and allied warships in these waters is a calculated counterweight to those actions. These deployments are not seeking confrontation, but they serve to maintain access, deny unilateral control, and reassure regional partners that the U.S. Navy and its allies are operationally committed—not just rhetorically committed—to a stable balance of power.

This operation fits within the larger U.S. Indo-Pacific strategy, which emphasizes forward presence, integrated deterrence, and strengthened alliances. For Australia, it reflects not only a shared interest in regional security but a growing role in its execution. As part of the AUKUS partnership and through continued joint operations, Australia is aligning more closely with U.S. doctrine, technology, and readiness standards. This isn’t symbolic diplomacy—it’s practical defense planning. Ships like Ballarat are not simply tagging along; they are critical contributors to multi-domain mission sets, including air defense, anti-submarine warfare, and surface action.

What’s most significant is the normalization of these joint operations. They are no longer extraordinary events; they are becoming standard operating procedure. That alone sends a message: the U.S. Navy and its allies are prepared, coordinated, and present. And they will remain so—day after day, deployment after deployment—not because of any temporary crisis, but because that is the posture required to maintain maritime order, deter coercion, and protect allied interests in the most strategically vital waterways in the world.

This approach is not escalatory, but it is assertive. It is grounded in the belief that deterrence is most effective when it is credible, persistent, and backed by actual capability. Exercises like this one between USS Dewey and HMAS Ballarat are one of the clearest demonstrations of that doctrine in action. They show that the United States is not just committed in principle to regional security—it is committed in practice, with real ships, real sailors, real weapons, and real allies operating together, professionally and confidently, in defense of shared national interests.