MANILA - A foreign armed attack on Philippine security forces will trigger the United States' obligations under the Mutual Defense Treaty, US Ambassador to Manila Sung Kim said on Wednesday.

"If there is an armed attack on Philippine forces, Philippine aircraft [in the West Philippine Sea], it will trigger US obligations under the Mutual Defense Treaty," the envoy told reporters on the sidelines of the US Independence Day celebration in Makati City.

He was referring to the 1951 pact between the US and the Philippines which binds the two countries to aid each other in the event of foreign aggression.

On June 9, a Chinese vessel hit and sank a Filipino fishing boat in the Recto (Reed) Bank in the West Philippine Sea, leaving 22 fishermen adrift. It was the latest incident of China's aggressive assertion of its sovereignty in the waters, the Philippines' exclusive economic zone in the South China Sea.

China has denied the incident was intentional and that the Chinese vessel abandoned the Filipinos. The Philippine fishermen were rescued by a Vietnamese vessel.

• 'No hit-and-run': Beijing denies boat abandoned Pinoy fishermen near Reed Bank

Kim said the Philippines and China should settle their disputes on the sovereignty issue in a peaceful manner.

Since the US is not a signatory to the United Nations Convention on the Law of the Sea, or the Law of the Sea treaty, the superpower will not intervene in the international dispute.

However, Kim said US forces "have to make sure that freedom of navigation and freedom of overflight are protected."

US Secretary of State Mike Pompeo earlier this year gave assurances that the US would respond to “any armed attack on Philippine forces, aircraft or public vessels in the South China Sea."

• US warns PH of China threat in South China Sea

- Report from Ina Reformina, ABS-CBN News