Chinese research vessels loiter near undersea cables more than any other nation

A Center for Strategic and International Studies analysis compared the movements of 200 research vessels from 47 countries and found that Chinese ships spent a statistically larger share of their time near critical undersea infrastructure in the Pacific than vessels from any other nation. The report says this persistent, disproportionate activity could indicate that China is using its civilian research fleet to collect underwater data, including seafloor terrain information relevant to submarine operations or possible sabotage. Research vessels can provide plausible deniability because they are not formally part of a country’s navy, even though the data they gather may have military value.

One example involved a ship from the Xiang Yang Hong fleet, which spent time near three undersea cables between July and October 2024. Those cables connect the United States with Australia, Indonesia, Singapore, Guam and other locations. The ships’ “lawnmower” routes are commonly used to survey the seabed and build detailed maps, though the reported activity does not establish that sabotage is planned. The concerns arise amid China’s disputes with South China Sea neighbors and its claims over Taiwan. The report also places the issue in a broader pattern: a separate account cited 500 Russian monitoring incidents near cables over five years, while Iran has threatened cable attacks in the Strait of Hormuz if conflict with the United States resumes.