美济礁
In 1999, Malaysia occupied Gabriela Silang Reef (Erica Reef) and Pawikan Reef (Investigator Shoal), causing the Philippines to protest further. Due to this pressure, with China's Mischief Reef just off Palawan and Vietnam's Pigeon Reef and Malaysia's Investigator Shoal just off Palawan, the Philippines decided to occupy Ayungin Reef (Second Thomas Reef) in 1999. No structure is built on the reef. Soldiers stationed there take shelter at "BRP Sierra Madre", a Philippine naval ship that was purposely run aground in the reef shortly before the Philippines decided to occupy it. Together with Rizal Reef (Commodore Reef), Ayungin Reef can give the Philippines a sentry advantage in stopping other countries' occupation of features nearest to the Philippines (see map below).