Thread by @GordianKnotRay

1/ANATOMY OF A SWARM: How #China sent its ships to swarm & intimidate the #Phlippines’ largest outpost in the West Philippine Sea, then scattered after its tactics were made public, 3-11 March 2023.
By 5 March the swarm of Pag-Asa Island was well underway. (1/9)
#SouthChinaSea

2/However, by 10 March—perhaps due to the #Philippines’ new transparency initiative—#China had apparently recalculated & decided that swarming was no longer in its interest. Only 10 ships remained in the Pag-Asa Cays. Where did the rest go?
(Hint: not very far) (2/9)

3/Maritime open-source intelligence (#OSINT) relies on a suite of tools. The automated information system (AIS) broadcast by most ships is the simplest, but it has limitations. We used AIS to track the arrival of 7 new PRC militia ships to the Pag-Asa Cays on 3 March. (3/9)

4/#China had 42 ships in the Pag-Asa Cays by 5 March. #Philippines-held Pag-Asa (a “rock” under @UN law) earns a 12nm territorial sea. Nearby PRC base at Subi Reef earns zero because it’s a “low tide elevation”--meaning in its original state it was below water at high tide. (4/9)

5/By 6 Mar we wondered if there was a rotation underway, as 4 militia ships were seen on AIS returning to port at Hainan Island,while one more ship deployed from Hainan to the Pag-Asa Cays. By this time the @coastguardph’s new transparency policy was beginning to take hold. (5/9)

6/Starting 8 March it seemed #China had made a recalculation based on the #Philippines’ recent transparency initiative. At least 3 of the (AIS-visible) militia ships started a meandering dispersal away from Pag-Asa, and we wondered if there were more.
Hint: yes—there were. (6/9)

7/Fortunately 10 March offered a clear day when we could go looking for ships not visible on AIS that might be lingering around. We found them. It seemed #China wasn’t enjoying the exposure of the @coastguardph’s new transparency policy & had scattered its swarming fleet. (7/9)

8/#China’s intimidation force dispersed mostly to the north & west in an apparent attempt to evade the #Philippines’ surveillance. Unfortunately for them the weather didn’t cooperate & can see how they’re hiding in plain sight—away from Pag-Asa but close enough to return. (8/9)

9/We can now see maritime gray-zone bullying tactics in near-real time. The #Philippines’ new transparency policy is a game-changer, but efforts like Project Myoushu at @StanfordGKC are also ready to support the free-and-open community to expose #China’s maritime bullying. (9/9)