When Philippine Coast Guard patrol ships BRP Malabrigo and BRP Malapascua arrived at Ayungin (Second Thomas) Shoal for the monthly rotation and resupply mission to the Philippines' outpost aboard BRP Sierra Madre on 30 June, they were greeted by an armada of Chinese ships, with two coast guard and seven militia ships surrounding the shoal. 

There was also an additional 90-meter vessel--not broadcasting an automatic information system (AIS) signal, but visible on satellite imagery--loitering near the Sierra Madre. Based on its size and location, this was likely either a People's Liberation Army-Navy (PLAN) vessel or a third China Coast Guard ship.

An additional seven militia ships lay just over the horizon in the vicinity of the nearby Chinese base at the artificially constructed Mischief Reef.

One of the two China Coast Guard ships, CCG 3103, made an extraordinary 650-kilometer trip from Scarborough Shoal to Ayungin Shoal, apparently for the sole purpose of contesting this resupply. It then returned directly back to Scarborough after the resupply was complete.

Ordinarily, two lightly armed, 45-meter Parola-class patrol vessels would not be cause for this heavy-handed response by China. Beijing seems to sending a message to the Philippines that its recent challenges to China's sovereignty claims over this part of the West Philippine Sea have been noted with considerable displeasure.

Notes: The 2016 Permanent Court of Arbitration ruling found that "there exists no legal basis for any entitlement by China to maritime zones in the area of Second Thomas Shoal." It further found that "[the] ‘nine-dash line’ thus cannot provide a basis for any entitlement by China to maritime zones in the area of Mischief Reef or Second Thomas Shoal that would overlap the entitlement of the Philippines to an exclusive economic zone and continental shelf generated from baselines on the island of Palawan."

Imagery credit: Planet Labs