On March 20, the Philippines announced that it had monitored over 220 Chinese militia boats at Whitsun Reef in a patrol earlier that month. In the two and a half months since, the Philippines has increased the level of its law enforcement and military patrols in the South China Sea beyond anything seen in recent years.

AMTI reviewed ship tracking data from commercial provider Marine Traffic and satellite imagery from Maxar and Planet Labs to evaluate Philippine patrols around disputed areas of the South China Sea over the past year. This analysis likely misses some patrols, particularly by naval vessels, that did not broadcast AIS. But the increase in activity by those that did is dramatic. From March 1 to May 25, AMTI observed 13 Philippine law enforcement or military vessels paying a total of 57 visits to waters around the Spratly Islands and Scarborough Shoal. This was a substantial increase over the previous 10 months (May 2020-Februray 2021), when 3 vessels were tracked making 7 total visits to contested features.

Not only the frequency, but also the location of patrols has changed. Prior to March, Philippine government vessels were almost exclusively seen traveling directly to and from Thitu Island, the Philippines’ largest outpost in the Spratlys. But recent patrols have included Second Thomas Shoal, which is occupied by the Philippines but patrolled daily by China, Whitsun Reef, where the recent militia swarm was detected, unoccupied Sabina Shoal near Second Thomas, and Scarborough Shoal, where China has maintained a permanent presence since 2012.

The Philippine Coast Guard (PCG) seems to have increased its patrols to Thitu and Second Thomas almost immediately after the public announcement about the militia presence on March 20. This presaged the public shift in focus by Philippine officials from just criticizing the Whitsun Reef militia deployment to documenting China’s paramilitary presence throughout the Spratlys.

Some recent patrols included encounters with Chinese law enforcement and militia vessels. In one publicized incident on April 27, the Philippine Coast Guard vessel Cabra and the Bureau of Fisheries and Aquatic Resources’ MCS 3002 and MCS 3004 dispersed seven Chinese fishing vessels thought to be members of the militia from Sabina Shoal. A Planet Labs satellite image captured the Cabra, followed by the MCS 3002 and 3004, driving off the Chinese vessels.

Since the Whitsun Reef incident, the Philippines has also stepped up patrols near Scarborough Shoal, bringing it into closer contact with the China Coast Guard (CCG). For instance, on April 24-25, the PCG sent two vessels—the BRP Sindangan and its largest ship, the BRP Gabriela Silang—near the shoal. A week later, National Security Adviser Hermogenes Esperon publicly condemned the “shadowing, blocking, and dangerous maneuvers, and radio challenges” conducted by CCG vessels in response. AIS data confirms that the Gabriela Silang and Sindangan conducted several loops around Scarborough on those two days, during which at least two CCG vessels, the 3102 and 3303, and one militia ship, the Qiongsanshayu 00317, were on-site.

The AIS signals from the Chinese vessels were too intermittent during that incident to verify Esperon’s claim of dangerous maneuvers. But AIS and satellite imagery paint a clearer picture of a more recent patrol on May 19, when the Philippines sent four vessels: the BRP Gabriela Silang, BRP Sindangan, BRP Habagat, and MCS 3005 to Scarborough.

On that occasion, the Philippine vessels sailed directly to within 10 nautical miles of the shoal—inside it’s contested territorial sea—where they were met by the CCG 3301 and 3102. The former began trailing the MCS 3005 as it circled around one side of Scarborough and the latter pursued the Habagat closely on the other before peeling off toward the larger Gabriela Silang. A satellite image taken at 9:50 a.m. local time captured the CCG 3102 just 400 meters from the Habagat:

During these patrols, Philippine vessels are almost always outsized and outgunned by their Chinese counterparts. In this case, the 27-meter Habagat, a tugboat, is less than half the size of the 73-meter CCG 3102, a Zhaoming-class patrol cutter.

The CCG 3303 and four Chinese fishing vessels, the Qiongsanshayu 00311, Yuezhanyu 08035, and the Zhongyue 62 and 63, were also present at Scarborough on May 19, though their AIS signals were too intermittent to observe whether they interacted with the Philippine vessels.

Vessels at Scarborough Shoal, May 19-20, 2021

Vessel Name Length (meters)
BRP Habagat 27
MCS 3005 30
BRP Sindangan 44.5
Chinese fishing vessels (average) 50
CCG 3102 73
BRP Gabriela Silang 84
CCG 3301, 3303 110

The Philippines’ increased patrol efforts send a message that Manila is determined to assert its rights. But they pale in comparison to China’s near-permanent coastguard and militia presence throughout the South China Sea. A limited number of PCG and BFAR vessels have the endurance to travel safely to the Spratlys and Scarborough. These few Philippine ships have embarked on staggered tours across the South China Sea every couple of weeks since March, spending only one or two days at contested features before moving on. Chinese vessels, by contrast, operate as sentries, staying at targeted features for weeks at a time and usually leaving only once a replacement has arrived to continue the watch.

Whether the Philippines will continue its current pace of patrols, and how China might react, is unclear. But while Manila’s combination of more public protest and greater presence seems to have had some success in dispersing Chinese vessels at Whitsun Reef and Sabina Shoal, it hasn’t impacted the overall number of Chinese vessels operating in disputed waters. The Whitsun flotilla has simply moved north toward other parts of the Spratlys. China shows no signs of dialing back its daily patrols around Second Thomas, and certainly not of leaving Scarborough. Still, the Philippines is drawing greater attention, and international condemnation, to China’s activities, particularly on the militia front.