On Monday, Reuters reported China Coast Guard and industrial fishing ship operations at Scarborough Shoal, the Philippines, which are arguably a violation of Philippine territorial sovereignty. The report said China is now allowing Philippine fishermen at the shoal, but restricting full access to the lagoon. The ratio of Chinese to Philippine fishing boats on Monday was about 10:1. China Coast Guard are typically armed, and have been shown to be armed at the shoal. Chinese ships at the shoal on Monday included at least two approximately 75-meter industrial fishing trawlers. In addition, according to Reuters, the Chinese Foreign Ministry confirmed that the China Coast Guard was at the shoal to “administer fishing and preserve the peace.” This is arguably a direct violation of Philippine sovereignty at what the Hague’s Permanent Court of Arbitration (PCA) found to be an “island” last year. The U.S.-Philippine Mutual Defense Treaty of 1951 applies to “islands”, so should be triggered by China’s continued armed occupation of Scarborough.

https://www.forbes.com/sites/anderscorr/2017/04/14/take-defense-treaty-action-for-philippine-sovereignty-in-south-china-sea/#13a3eeab6ed3