China's expansion of deep-sea exploration arouses military concerns

By Wu Qiaoxi | 2025-04-01

China is heavily investing in the world's largest fleet of research vessels to map the ocean floor, conduct scientific research and potentially support military operations, an effort some observers could pose a security threat to the United States and its allies.

China's Xiangyanghong 01 and Dongfanghong 3 advanced research vessels have been collecting comprehensive hydrological data in the eastern Indian Ocean in recent weeks, the Wall Street Journal reported March 12.

In recent years, Chinese research vessels have been highly active in global oceanographic studies, collecting data on seabed topography, ocean currents and other hydrological matters.

While the information could greatly benefit research in climate change, ocean resource management, submarine cable installation and deep-sea mining, it could give the People's Liberation Army (PLA) a strategic advantage in combat.

Oceanographic research data can be repurposed for military use, such as improving the accuracy of mine deployment, enhancing sonar detection and helping submarines evade tracking.

"If that data has value to the Chinese military and they want access to it, they will get it," Matthew Funaiole, a senior fellow at the China Power Project at the Center for Strategic and International Studies (CSIS), told the Wall Street Journal. "There's no firewall in place."

Former CIA intelligence officer Nick Thompson told The Cipher Brief that China's actions extend beyond scientific research and are "closely linked to intelligence gathering."

Chinese research vessels frequently operate near India, Australia, the Philippines and Taiwan. These activities appear to test territorial boundaries and gradually "normalize such actions," Thompson said.

Suspect behavior

Between 2020 and 2024, Chinese survey vessels collectively spent hundreds of thousands of hours conducting operations worldwide, research from CSIS indicates.

Of China's 64 active survey vessels, more than 80% are directly affiliated with the PLA or its associated institutions.

Some of these vessels have visited military ports and engaged in suspect behavior, such as impersonating other ships, disabling identification systems and evading radar tracking. These findings suggest their involvement in advancing Beijing's geopolitical agenda.

Chinese research vessels have repeatedly entered other countries' Exclusive Economic Zones, sparking protests from Japan, India and other governments.

The way these hydrological data are collected -- combined with the blurred lines of civilian and military in China -- comes together to "concern India," Anushka Saxena, a research analyst with the Takshashila Institution, an Indian think tank, told the Journal.

Some research missions include "comprehensive observations in the field of military oceanography," Chinese media have acknowledged.

The findings from these expeditions could enhance the PLA's operational capabilities, enabling it to extend military influence into distant oceans and deep-sea environments.