The January drills across the South China Sea are best read as another demonstration of how unmanned undersea systems have shifted from laboratory curiosities to operational instruments of statecraft. Beijing’s recent announcement of routine exercises following a joint US‑Philippine patrol underscores that these drills now occur in a contested environment where persistent, low‑profile platforms below the surface matter as much as ships and aircraft on it.

Two facts shape the operational logic: first, oceanographic sensing underpins modern undersea warfare; second, the platforms that collect that sensing have proliferated and diversified. Analysis of Chinese research missions since 2020 identified scores of state‑affiliated survey vessels and documented the routine deployment of underwater gliders and profiling floats to build a near‑real‑time picture of hydrological conditions. One expedition in 2019 and 2020, for example, released a dozen advanced gliders and some 15 profiling floats during a single long voyage. That data feeds acoustic models, buoyancy profiles, bathymetry maps and other inputs that change how submarines and anti‑submarine systems plan operations.

On the other side of the Pacific, the United States has accelerated fielding of larger autonomous undersea platforms. In December 2023 the Navy accepted delivery of its first extra‑large unmanned undersea vehicle test asset system, an Orca XLUUV test asset built to host modular payloads for mission types that range from persistent sensing to mine warfare. Congressional and service documents make clear the XLUUV family sits at the center of an effort to distribute naval capabilities across more numerous, lower cost nodes. That architectural impulse is why we now see both small gliders and large uncrewed submarines enter the operational calculus.

What does this convergence mean for drills in the South China Sea? Practically, UUVs turn exercises into layered campaigns: surface ships and aircraft provide visible deterrence and command and control; unmanned surface vessels and aerial drones extend the eyes and links; UUVs probe, persist and map below. Use cases exercised during multinational events and experiments already include anti‑submarine sensing, mine countermeasures, bathymetric surveying and demonstration of manned‑unmanned teaming. The XLUUV concept explicitly contemplates payloads such as autonomous mines and sensor packages that alter the geometry of maritime denial.

That utility creates friction points. The seizure of a U.S. ocean glider by a Chinese naval vessel in December 2016 is the clearest precedent that small, intendedly benign oceanographic assets become geopolitical flashpoints when operated in contested waters or perceived as dual use. In that incident China retrieved a UUV that the U.S. said was operating in international waters, prompting an official U.S. protest and eventual return of the device. The legal and normative status of unmanned vessels at sea remains ambiguous enough that routine recovery or interdiction is a real risk when states feel their security is implicated.

Operational risks fall into three buckets. The first is misidentification and escalation. An uncrewed platform operating autonomously, especially one that cannot be visually associated with a launching ship, creates split second decision problems for crews that encounter it. The second is attribution and exploitation of data. Bathymetric and acoustic information can be repurposed to improve submarine routing or to refine targeting for sub‑sea weapons. The third is survivability and defense. UUVs are valuable but many classes are noisy, communications constrained and vulnerable to capture or spoofing in littoral waters. These risks are identified in service and congressional studies on large unmanned maritime platforms which also note the need for robust CONOPS, C2 resilience and legal frameworks before mass deployment.

From a systems engineering perspective the most immediate technical challenge is not propulsion or endurance alone. It is the integration of reliably secure command and control, positive identification signatures, and robust autonomy that can degrade gracefully in the face of contested communications. Persistent gliders report via satellite when they surface. XLUUVs promise longer endurance and more sophisticated payloads, but they also require secure launch and recovery sequences and clear rules for what constitutes a safe operating envelope in proximity to other states’ forces. Absent these safeguards the chance of inadvertent incidents rises as density of platforms increases.

Policy choices will determine whether undersea unmanned systems stabilize or destabilize the region. Three pragmatic measures would reduce risk while preserving legitimate missions: 1) establish bilateral or multilateral technical protocols for UUV identification and radio‑frequency behavior in contested waters; 2) expand notification and liaison mechanisms for joint exercises that include unmanned sub‑surface assets; and 3) accelerate investment in cooperative seabed and acoustic mapping exchanges that separate benign scientific collection from intelligence collection in practice, not only in rhetoric. These steps will not eliminate competition, but they reduce the likelihood that an unmanned glider or a modular XLUUV payload becomes the spark for broader escalation.

Finally, planners should treat UUVs as amplifiers of policy rather than substitutes for it. Technology is lowering the cost of presence under the sea, but presence without rules and transparency is not deterrence. As both state and non‑state actors integrate undersea autonomy into drills and deployments in the South China Sea, the balance between operational advantage and geopolitical risk will hinge on doctrine, not hardware. The next year of exercises will therefore serve as a diagnostic: will regional navies use UUVs to increase predictability and shared situational awareness, or will they let undersea automation become another layer in a growing fog of strategic uncertainty?