Gray zone activity is a constant in modern great power competition. Authoritarian states use indirect ways and means that fall beneath the threshold of armed force to set conditions for both future military operations and long-term coercive campaigns. This approach, termed “advancing without attacking,” is a central feature of how the Chinese Communist Party (CCP) pressures Taiwan and other states. China has waged disinformation campaigns around Taiwanese elections, stolen intellectual property to accelerate its technological rise, and seized disputed border territory by quietly building villages, all while avoiding direct military confrontation. These operations often rely on ambiguity, plausible deniability, and the strategic use of nonmilitary assets. In the maritime domain, China has consistently used civilian vessels—especially fishing boats—as tools of statecraft in contested waters. While analysts have focused heavily on the People’s Liberation Army Navy (PLAN) maneuvers near Taiwan, less attention has been paid to the role of unmarked or dual-use vessels operating in parallel with the PLAN. These ships can, and do, conduct surveillance, harass foreign vessels, and reinforce territorial claims under the cover of commercial activity. Examples include using civilian ships to drop anchors and thereby sever undersea cables, deploying fishing fleets to overfish and damage maritime habitats, and leveraging dual-use infrastructure to project a coercive presence. Yet, how can policymakers and national security analysts separate this maritime gray zone activity from international trade and commerce? How can intelligence agencies and the U.S. Department of Defense (DOD) at large collaborate to identify specific vessels while facing large volumes of data under budget constraints? To answer these questions, the Futures Lab proposes a classification framework that combines geospatial data with behavioral, time, and vessel attribute manipulation to flag vessels engaging in suspicious activities. This report examines how China may be using ostensibly civilian maritime assets as part of a coordinated campaign around Taiwan that combines coercion and intelligence operations to set operational conditions in the event of direct conflict. Specifically, this study profiles vessels in two ways. First, it examines fishing vessels that spend significant time in military drill zones without engaging in active fishing, as they are more likely to be participating in state-directed gray zone activity. The second profile encompasses purported fishing vessels that exhibit AIS anomalies—such as going dark, changing identifiers, or reducing or attempting to mask their AIS movements—while in or near known drill areas. These behaviors may be attempts to mask the vessels’ movement to avoid scrutiny, and they suggest that these ships are likely to be engaging in gray zone activity. The classification framework used in this study whittled down nearly 12,000 vessels traveling near Taiwan to an estimated 128–209 ships that fit into one (or both) of the two profiles and, thus, are likely engaged in gray zone activities. In addition, using a geospatial approach to measure the concentration of positions, the research team highlighted the study’s classification framework findings of one specific profiled vessel, demonstrating that the vessel had, in fact, spent the vast majority of its time in known Joint Sword drill zones. In effect, the classification framework cuts down on the man-hours needed to analyze vast quantities of data, positioning federal intelligence analysts responsible for maritime security in East Asia to be able to quantify gray zone activities.
Signals in the Swarm: The Data Behind China’s Maritime Gray Zone Campaign Near Taiwan
