"What we are looking to do is to bolster our Philippines allies' capabilities and ability to continue to operate lawfully in its waters, and to stand up to detect challenges that it faced in recent months," Rapp-Hooper said during a discussion at the American Enterprise Institute.
Rapp-Hooper said the US-Philippines mutual defense treaty applies with respect to the South China Sea and public vessels, and the applicability of the treaty is clear.
The Philippine Foreign Ministry said earlier that the Philippines and China have agreed on principles to de-escalate the situation in the South China Sea regarding delivering personnel and cargo to a grounded Philippine warship on the disputed Ayungin Shoal.
The territorial affiliation of a number of islands and reefs in the South China Sea has been the subject of disputes between the Philippines, China and several other countries.
In 2016, the Permanent Court of Arbitration in the Hague ruled in the case brought about by the Philippines that China has no grounds for territorial claims in the South China Sea. The court ruled that the islands are not a disputed territory and do not constitute an exclusive economic zone. China refuses to recognize or accept the ruling.