China’s deployment of research and survey vessels in contested waters is a key component of its maritime gray zone strategy. These vessels, often presented as civilian or scientific, are frequently state-owned or operated by entities with close military ties. These missions blur the line between legitimate scientific research and covert intelligence gathering or strategic signaling, allowing China to expand its maritime presence while maintaining plausible deniability.

How the Tactic Works

• Dual-Use Operations: Chinese research vessels conduct oceanographic surveys, resource mapping and data collection, which can support both civilian and military objectives. Intelligence gathered can inform naval operations, submarine deployments, locations of sensitive undersea cables and resource exploitation plans.

• Threatening Patterns and Symbolism: Survey ships sometimes deviate from standard survey patterns, as seen in the May-June 2023 Xiang Yang Hong 10 incident off Vietnam, where the vessel’s path appeared to trace the Chinese character “中” (“China”), possibly as a form of psychological signaling or territorial assertion.

• Escorted Incursions: Survey vessels are often accompanied by China Coast Guard and maritime militia ships, providing protection and reinforcing China’s territorial claims. The presence of escorts deters interference from regional states and complicates responses, as direct confrontation with “civilian” vessels risks escalation or international criticism.

• Going Dark: Research vessels may disable their AIS transponders (“going dark”) before conducting sensitive operations, obscuring their activities and intentions.
• Legal and Diplomatic Cover: China routinely claims its survey activities are lawful based on its excessive maritime claims--not merely dismissing protests from other countries and exploiting legal ambiguity, but using the survey as a means of asserting its sovereignty or jurisdiction.

China’s use of research and survey vessels serves several overlapping strategic aims in its gray zone maritime campaign. By systematically gathering data on undersea resources, these missions support Beijing’s efforts to identify and secure valuable economic assets in disputed areas, often at the expense of neighboring states’ interests. 

At the same time, the regular and highly visible presence of these vessels--such as the monthlong survey of Malaysia's EEZ by the Haiyang Dizhi 8 in the summer of 2023--helps normalize China’s activities and reinforce its territorial claims, gradually shifting perceptions of legitimacy and control in contested waters.

Beyond resources and territory, these operations are fundamentally about intelligence. Scientific surveys double as covert intelligence collection, mapping the seafloor, monitoring foreign military and commercial activity, and enhancing China’s operational awareness for both present and future contingencies. The combination of civilian cover and military escort is designed to deter interference by regional actors, signaling China’s resolve while complicating any direct response—since confronting a nominally civilian vessel risks escalation and international criticism.

This approach is effective because it leverages plausible deniability and incrementalism. The civilian status of research ships blurs the line between legitimate activity and coercion, making it difficult for targeted states to justify forceful responses without appearing provocative themselves. These operations are part of a broader “salami-slicing” strategy, advancing China’s interests step by step below the threshold likely to trigger open conflict, while steadily accumulating advantages in the region.

More examples:

Indian Ocean (2025): In the spring of 2025, China’s largest “silent” research vessel, Dong Fang Hong 3, conducted a month-long survey of the Ninety East Ridge, a strategically important underwater feature in the Indian Ocean. Although the survey was not illegal, the vessel’s advanced technology and low-noise design raised concerns in India, as the data collected could enhance Chinese submarine operations and sonar performance. Though legal, the timing of this mission coincided with sensitive Indian naval activities, further fueling suspicions about intelligence-gathering objectives.

Suspicious activity (2023–2025): The Xiang Yang Hong 01 mapped approximately 500,000 square kilometers of the Ninety East Ridge and was documented switching off its AIS transponder near Indonesian waters, a maneuver that raised diplomatic scrutiny. In February 2025, it operated alongside Dong Fang Hong 03 near the Andaman and Nicobar Islands during India’s ballistic missile tests, reinforcing concerns about covert surveillance.

Australia and New Zealand (2023, 2025): In 2025 the Chinese deep-sea research ship Tan Suo Yi Hao sailed around Australia after a month off New Zealand's coast, officially for scientific exploration. However, its activities—such as pausing over the Diamantina Trench and deploying a crewed submersible—sparked speculation that it could be servicing seabed acoustic sensors--possibly laid in 2023--to gather intelligence or support future submarine operations.

Survey near the Senkaku Islands (October 2023): A Chinese research vessel, the Xiang Yang Hong 18, was detected by the Japanese coast guard conducting suspicious maneuvers near the disputed Senkaku Islands, an area frequently at the center of maritime tensions between China and Japan.

China also regularly harasses its neighbors' research operations that occur within its claimed waters, such as the October 2024 shadowing of Indonesia's survey within its EEZ in the North Natuna Sea. 

Survey harassment can sometimes get even more direct, employing complementary gray zone tactics like swarming, blocking, ramming and cable-cutting.

Routine Chinese survey operations in the South China Sea, East China Sea, and Taiwan Strait are no longer isolated events—they have become a defining feature of the region’s maritime landscape. These missions, often met with diplomatic protests from countries like Vietnam, the Philippines, and Japan, consistently raise tensions and test the resolve of neighboring states to defend their own maritime claims.

Ultimately, China’s research and survey vessel operations are a textbook example of gray zone strategy in action. By leveraging dual-use platforms, exploiting legal ambiguity and conducting information operations under a veneer of scientific legitimacy, Beijing steadily asserts control, gathers critical intelligence and coerces regional actors—all while staying just below the threshold that might provoke direct military confrontation.