China Coast Guard (CCG) vessels have been harassing a drilling rig operating in a Vietnamese oil and gas block near Vanguard Bank, an underwater feature in the South China Sea, since June. Meanwhile, a large contingent of CCG ships have since July been escorting the Chinese state-owned survey ship Haiyang Dizhi 8 operating off the Vietnamese coast farther north. These actions have drawn attention to the CCG’s increasing role in asserting Chinese claims over seabed resources throughout the South China Sea. They also highlight how the CCG’s access to newly-built port facilities on artificial islands in the Spratlys allows it to sustain such deployments. But less appreciated is the persistent presence the CCG maintains around several symbolically important features in the South China Sea: Luconia Shoals, Second Thomas Shoal, and Scarborough Shoal.

AMTI has identified 14 CCG vessels broadcasting automatic identification system (AIS) signals while patrolling these features over the last year. These are just a subset of the CCG fleet operating in the South China Sea, and many others loiter at Chinese bases in the Paracels and Spratlys or patrol around the outposts of other claimants (such as Thitu Island).

The vessels patrolling Luconia, Second Thomas, and Scarborough most often belong to the Shucha II and Zhaolai classes. These vessels are largely unarmed, except for water cannons and small arms, but are much larger than the law enforcement or most navy ships of their neighbors. This makes them ideal for operations that might involve threatening collisions and, if necessary, shouldering other vessels to drive them away without using lethal force. More heavily-armed vessels like the Zhaoduan and Zhaojun class, both of which have a 76 mm cannon, have also patrolled these areas but are more frequently seen in larger deployments such as those currently occurring off the Vietnamese coast or around Philippine-held Thitu Island starting in December 2018.

What really sets the vessels patrolling Luconia, Second Thomas, and Scarborough apart is that it appears they want to be seen. Most commercial vessels over 300 tons are required to broadcast AIS for collision avoidance, but military and law enforcement vessels have discretion about when and where to do so. CCG vessels elsewhere in the South China Sea often do not broadcast AIS or do so only when entering and leaving port. But those patrolling Luconia Shoals, Second Thomas Shoal, and, to a lesser degree, Scarborough Shoal appear to broadcast far more frequently. There was at least one ship broadcasting from Luconia on 258 of the last 365 days. At least one was broadcasting at Second Thomas on 215 days, and from Scarborough for 162 days.


The Haijing 3308, a Shucha II-class CCG patrol vessel, is emblematic of this behavior. Between September 2018 and September 2019, AIS signals show the 3308 undertook patrols around Second Thomas Shoal, Scarborough Shoal, and Luconia Shoals, in addition to participating in the harassment of Vietnamese oil and gas operations in Block 06-01 and escorting the Chinese survey ship farther north. It also made use of the Chinese port facilities at Subi Reef between patrols.

This patrol pattern highlights an important CCG objective in the South China Sea—to create a routine, highly visible Chinese presence at key sites over which Beijing claims sovereignty but does not have any permanent facilities. Why Luconia, Second Thomas, and Scarborough?

Luconia Shoals is a symbolically important series of reefs off the coast of Malaysia’s Sarawak state which China seems determined to control without physically occupying. Beijing, along with Taipei, consider them part of the disputed Spratly Islands despite their geographic distance from that group. One of the reefs, Luconia Breakers, may include a small sandbar above water at high-tide, but the rest are entirely underwater. CCG vessels have been patrolling Luconia regularly since September 2013. In fact, one of the CCG vessels now harassing Vietnamese operations near Vanguard Bank engaged in similar intimidation of a drilling rig in a Malaysian block near Luconia Breakers in May. The Malaysian government has not acknowledged that harassment and generally avoids mentioning the years-long CCG presence. But authorities are clearly aware, as evidenced by Royal Malaysian Navy vessels that infrequently monitor the Chinese patrols. For example, RMN Warships 3502 and 176 each patrolled near the Haijing 3306 at Luconia Shoals for at least two days in September and October 2018. Most recently, the Ka Bunga Mas 5, a Malaysian navy auxiliary ship, has been operating as close as 2 nautical miles from the Haijing 5401, which began patrolling the area on September 22.

Second Thomas Shoal is an entirely underwater reef less than 20 nautical miles from Mischief Reef, China’s largest outpost in the Spratlys. In response to China’s occupation of Mischief in 1994, the Philippines in 1999 intentionally grounded a World War II-era tank landing ship, the BRP Sierra Madre, on the reef. The ship has since served as a permanent outpost for a small contingent of Filipino troops, despite Chinese demands that it be removed. China increased its patrol presence near Second Thomas Shoal in May 2013 and blockaded the troops on the Sierra Madre for several weeks in March 2014. More recent harassment reports have included the buzzing of a Philippine resupply mission by a CCG helicopter in May 2018 and a report from the Philippine Department of National Defense that the Haijing 3305, another Shucha­ II­-class vessel, blocked the route of three resupply vessels in May 2019.

Far from being unusual, the 3305’s deployment around Second Thomas was part of a regular pattern of near-constant CCG patrols near the Sierra Madre. The more recent patrols of its sister ships, the Haijing 3307 in July and Haijing 3306 in August, are illustrative.

The third site most often frequented by these CCG patrols broadcasting AIS is Scarborough Shoal, which has been at the heart of Sino-Philippine tensions since 2012 when China effectively seized control of the feature. CCG as well as Chinese maritime militia vessels have maintained a constant presence at Scarborough ever since, with at least one Chinese vessel always anchored just inside the only channel into the reef’s lagoon. Since late 2016, and sporadically between 2012 and 2016, the CCG has allowed Filipino fishing around the perimeter of the lagoon. But those activities happen under the watchful eye of the Chinese vessels, which reportedly harass and extort fishers.

CCG vessels frequently broadcast AIS while patrolling Scarborough, but not as consistently as they do at Second Thomas and Luconia. This may be because, unlike those other reefs which are effectively administered by the Philippines and Malaysia, China is firmly in control of Scarborough. Every Filipino fisher returning from the reef confirm China’s presence, and satellite imagery shows that Chinese vessels remains on-station inside the lagoon. This might explain why the CCG vessels which frequently patrol around the shoal do not feel the same need to broadcast their position as a declaration of sovereignty, though they also do not necessarily bother to shut off their transceivers either.

Chinese government vessels stationed inside Scarborough Shoal, May 15, 2019

The pattern of Chinese patrols at these features has grown more consistent in recent years, and especially with the completion of harbor facilities at its bases in the Spratly Islands. There don’t appear to be any other contested areas where CCG presence is so persistent, and where China clearly wants regional counterparts to know they are present. Beijing has evidently taken a special interest in Luconia, Second Thomas, and Scarborough Shoals. It seems to be wagering that if it can maintain a semi-permanent CCG presence for long enough, regional states will eventually accede to its de facto control of those areas. And if that strategy succeeds at Luconia and Second Thomas (as it arguably already has at Scarborough), it will serve as a compelling blueprint for extending Chinese administration across other reefs and shoals.