Chinese ships enter Ayungin

(UPDATE) A SWARM of Chinese ships have ventured inside the Ayungin (Second Thomas) Shoal in what a maritime security expert described as an «unprecedented» event.

Chinese ships also lingered in the shoal for 24 hours more after Sunday's confrontation with Philippine supply boats.

Ray Powell, director of SeaLight and Project Lead for Project Myoushu at Stanford University's Gordian Knot Center for National Security Innovation, said the Chinese blockading force usually return to their base in Panganiban (Mischief ) Reef once the Philippine supply boats and their escorts finish their mission to deliver provisions to the troops stationed in the derelict Navy ship Sierra Madre.

Powell said satellite imagery taken on Monday showed «an extraordinary» number of 11 Chinese vessels inside the shoal and 27 other ships surrounding Ayungin, including vessels involved in Sunday's incident.

He said two of the Chinese vessels were «rafted together» near the northwest corner of the shoal about 2 kilometers south of where the Sierra Madre was grounded.

Powell said none of the ships had their broadcasting automatic information system (AIS) on. He said on Thursday the Chinese vessels remained around the shoal until Monday afternoon, with some even venturing inside.

«It's quite rare to see Chinese vessels enter the shoal's interior at all, but 11 is certainly the highest number we've yet observed,» he said.

«This highly unusual invasion of the shoal's interior appears to have been a calculated show of force by Beijing,» he said.

Meanwhile, 27 Chinese militia ships and the China Coast Guard (CCG) vessel 5402, which was involved in several confrontations with Philippine vessels, were detected through AIS around the shoal, said Powell.

More ships were outside the shoal, including CCG 21556, the ship that fired its water cannon at and collided with the Unaiza May 1, the supply boat that had on board Armed Forces of the Philippines Chief of Staff Gen. Romeo Brawner and Western Command's Commander Vice Admiral Alberto Carlos on Sunday.

Powell said this capped off a «deeply concerning and escalatory weekend of very aggressive behavior» by China.

Philippine vessels and the resupply boats were also