china Unmanned Submarine Deployed to South China Sea

Defence affairs - Def-Geopolitics

In a dramatic move to accelerate its naval modernization, China has quietly deployed the world's largest unmanned submarine to disputed waters in the South China Sea.

These giant vessels, categorized as “XXL” or extra-extra-large uncrewed underwater vehicles (XXLUUVs), far exceed the size of all Western platforms and represent a major leap in Beijing’s autonomous underwater warfare capabilities.

Temporarily stationed around Hainan Island, this new platform marks a significant moment in the aspirations of the People's Liberation Army Navy (PLAN) to dominate undersea space in the Indo-Pacific.

Beijing has not made any official confirmation of the unmanned submarine, reflecting the level of secrecy and strategic importance of the country's unmanned naval military project.

The development was first revealed through open source intelligence (OSINT), when defense analyst HI Sutton reported its presence in Naval News , supported by satellite imagery as well as technical analysis.

The move comes as tensions rise in the South China Sea, with the PLAN seeking to shift the balance of power in one of the world's most strategic and disputed maritime zones.

The timing of the delivery of this giant platform is also symbolic, as it comes as the United States and its allies are increasing freedom of navigation operations and joint patrols in the waters concerned.

By placing this extraordinary asset in Hainan, Beijing is signaling that the South China Sea will be used as a testing ground and forward operating base for the country's most advanced maritime technology.

The move also highlights China's shift in doctrine towards the use of unmanned systems as a cost-effective method of projecting power, without exposing their sailors to direct risk.

For regional countries such as Vietnam and the Philippines, the existence of the XXLUUV reveals a widening technology gap with the PLAN, while also raising new concerns about Beijing's ability to implement undersea blockades in times of crisis.