The Center for Strategic and International Studies (CSIS) found a statistically significant association between Chinese-flagged research vessels and a greater share of observed time near subsea infrastructure on the high seas. The analysis covers vessel activity from January 1, 2020, through December 9, 2025, and describes a fleet-level pattern; CSIS says it cannot establish the intent of an individual voyage.
That finding complements a U.S.-China Economic and Security Review Commission (USCC) assessment of vulnerabilities across U.S. trans-Pacific cable systems. Together, the reports describe exposed routes and vessel activity, while leaving individual missions to be assessed on their own evidence.
What the USCC cable-risk index identifies
Published September 22, 2026, the USCC report introduced the Trans-Pacific Cable Gray Zone Vulnerability Index, which ranks vulnerabilities across U.S. trans-Pacific cable systems. The index considers factors such as route depth, nearby shipping traffic, cable ownership, maritime claims and connections to Taiwan, according to Ars Technica’s account of the assessment.
The USCC identifies routes linking the United States with Taiwan, Japan and the Philippines as especially exposed. It also flags connections to Hawaii and Guam, where it says redundancy options are limited. Ars Technica reported that Google’s TPU project, Meta’s ORCA cable and E2A were among the index’s five highest-risk projects. Verizon co-owns E2A with firms in Japan, South Korea and Taiwan.
What CSIS measured about research vessels
CSIS analyzed Automatic Identification System (AIS) movement data for 223 research, survey, dive, special and fishery-patrol vessels. The study compared Chinese vessels with fleets from 47 other countries. To account for imprecise cable locations, the researchers used a one-kilometer buffer around mapped cables and pipelines when linking vessel positions to nearby infrastructure.
In its baseline statistical model, the China-flag coefficient was 0.0315, with p < 0.001, for the share of observed high-seas time near subsea infrastructure. That coefficient describes an association in the model; it is not a measure of attack probability. The model’s adjusted R² was about 1.3%, meaning it explained a small share of variation in the data. CSIS says the fleet-level result does not establish the purpose of any specific mission.
Ke Xue’s reported 2024 voyage
In a case study, CSIS described the Chinese-flagged research vessel Ke Xue making survey-like movements near cable corridors during a northern voyage from July 15 to August 28, 2024. The account places the vessel near the Russian government-owned Polar Express cable in the Bering Sea. These reported movements are one case within the broader study; CSIS’s fleet-level analysis does not identify the vessel’s intent.
How cable disruptions could affect Pacific routes
The USCC says a single cable disruption could overload capacity on some direct routes between the United States, Taiwan, Japan and the Philippines, forcing traffic onto slower, less direct paths. Multiple simultaneous disruptions could overwhelm trans-Pacific capacity and require wider global rerouting. These are modeled scenarios. The USCC also says most cable breaks are accidental or natural.
NeoTeo has covered a separate regional case in its report on proposed UK cable-security rules and reported vessel movements near British routes.
What the reports recommend
The USCC recommends shared maritime-awareness systems among allies, cable patrols, common incident-response protocols, penalties and exclusion zones, along with greater repair capacity and network resilience. CSIS proposes sharing information about suspicious activity, coordinated law-enforcement patrols on the high seas, regional repair hubs and multinational repair fleets. These are recommendations from the reports, not descriptions of measures already put in place.
The USCC assessment and the CSIS vessel analysis address different parts of the problem: route exposure and a statistical pattern in vessel activity, respectively.
