After years of consistency in patrolling all corners of Beijing’s nine-dash line claim, the China Coast Guard (CCG) made a major shift in 2025 to focus its efforts on Scarborough Shoal and Sabina Shoal. Analysis of AIS data from commercial provider Starboard Maritime Intelligence indicates that while China’s overall patrol volume has increased compared to 2024, this effort has become more concentrated at Scarborough and Sabina, showing a clear reallocation of CCG resources toward flashpoints between China and the Philippines.
China Coast Guard Patrols in the South China Sea
2025
AMTI examined AIS data for the calendar year 2025 to measure the number of days CCG vessels patrolled six locations in the South China Sea: Luconia Shoals, Sabina Shoal, Scarborough Shoal, Second Thomas Shoal, Thitu Island, and an area at the southwestern edge of the nine-dash line encompassing portions of Vietnam’s, Indonesia’s, and Malaysia’s exclusive economic zones. As is always the case, AIS data provides only a minimum estimate of CCG activity, with the true volume of patrols almost certain to be higher due to signal gaps as well as the sometimes deliberate disabling of AIS transponders.
To assess trends in CCG activity, AMTI measured patrols using two metrics: ship days, defined as the sum of each day spent by a CCG vessel at each location, and calendar days, which are the number of distinct days during the year in which at least one CCG ship was observed at each area.
In 2025, CCG patrols across the six locations amounted to 2,183 ship days, showing an increase from 1,939 ship days in 2024. This coincided, however, with a major shift in patrol effort directed toward Scarborough Shoal and Sabina Shoal. As a result of this reallocation, CCG ship days at several other features saw a decline—from 364 to 257 at Luconia Shoals; 288 to 131 at Second Thomas Shoal; 351 to 240 at Southwest/Vanguard Bank; and 281 to 51 at Thitu Island.
Increased Presence at Scarborough Shoal
Beijing maintained an unprecedented level of presence at Scarborough Shoal in 2025. The total number of CCG ship days more than doubled from 516 in 2024 to 1,099 in 2025, with patrols observed on 352 calendar days.
As previously reported, the CCG’s presence at Scarborough has expanded to include a wider area east of the shoal, with patrols in some cases clearly monitoring the eastern edge of Beijing’s nine-dash line claim that Philippine vessels cross on their way to the shoal. AIS data alone shows a daily average of three CCG ships active around Scarborough, but the true presence was almost certainly higher. Although AIS data shows a 12-day gap between February 17 and 28, the Philippine Coast Guard reported that CCG vessels remained active at Scarborough during this period.
Expanding Areas
Patrols around Sabina Shoal also significantly increased in 2025, both in volume and scope. The number of ship days the CCG spent patrolling near Sabina nearly tripled from 139 in 2024 to 405 in 2025. And while patrols in previous year focused on the immediate vicinity of the feature, 2025 operations expanded southward, encompassing a wider area that includes other nearby unoccupied features, such as Half Moon Shoal.
The expansion of patrol coverage at Scarborough and Sabina resembles the earlier expansion of CCG patrols at Vanguard Bank in 2024 to encompass a wider area including both Indonesian and Malaysian maritime claims. In 2025, this shift in the focus of the CCG’s southwestern patrols has become even more pronounced, with vessels in this area spending the majority of their time (261 calendar days) in the northeastern reaches of Malaysia’s EEZ and making only short trips (totaling 42 calendar days) to Vanguard Bank to keep tabs on Vietnamese oil and gas activity.
Taken together, the diversion of effort toward Scarborough and Sabina along with the change in geographic scope of multiple patrol areas makes 2025 witness to the biggest evolution in CCG behavior since AMTI began conducting regular AIS analysis of CCG patrol patterns in 2019.
Cover photo: JAM STA ROSA/AFP via Getty Images
