Two months ago SeaLight documented the seasonal return of the People's Republic of China's (PRC) Spratly Backbone Fishing Vessels to Sabina Shoal. We were not the only ones to take note, however. The Philippine Coast Guard (PCG) was also concerned, and last month dispatched the BRP Teresa Magbanua to investigate. 

The image above, taken on 8 May and provided by SeaLight's imagery partners at Planet Labs, helps tell the story of the 97-meter BRP Teresa Magbanua--visible along the left edge--facing off against the similarly sized China Coast Guard 3303, while a host of smaller PRC coast guard and militia ships were spread across the southeastern part of the shoal. 

These included many of the "rafted" vessels we noted in our March report, as well as those at the northwest end of the shoal, which can be seen in the center and along the right edge of this 21 April image provided by our imagery partners at SkyFi.

China responded to the arrival of the PCG ship in characteristic fashion, sending an armada over from Mischief Reef in an attempt to overwhelm and intimidate the PCG ship. 

How many ships and aircraft did the PRC send? According to the PCG, a lot:

The constant presence of rafted vessels is normally sufficient cause for concern, as China uses rafting as a form of "floating outposts" to normalize its presence and establish its sovereignty claims. What the Philippines fears, however, is that China has already begun to enact plans to create a more permanent outpost at Sabina. 

In fact, Manila claims to have found evidence that China may already be laying the literal groundwork by dumping mounds of dead coral on top of the underwater reefs:

China, of course, has a history of artificial island building and militarization, and today uses some of these--including the aforementioned Mischief Reef--as power projection platforms from which to expand its effective control of features within its neighbors' lawful exclusive economic zones.

The Philippines is especially concerned about Sabina Shoal, since it lies just 75 nautical miles from the coast of Palawan. Was China to succeed in building a military base there, it would be the nearest base to Philippine shores, as SeaLight's graphics partner Ian Ellis-Jones recently laid out in his helpful map of contested South China Sea features.