PRESIDENT Rodrigo R. Duterte should let the Philippine Navy join war games in the South China Sea after China passed a law allowing its coast guard to fire at foreign vessels in the disputed waterway, political analysts said.

“The President should now allow the Philippine Navy to join drills in the South China Sea, especially that Beijing no longer honors diplomatic protests,” Marlon M. Villarin, a political science professor from the University of Santo Tomas (UST), said in a Zoom Meetings interview. “We have to raise the flag in the disputed waters.”

The Chinese law allows its coast guard to “take all necessary measures, including the use of weapons when national sovereignty, sovereign rights and jurisdiction are being illegally infringed upon by foreign organizations or individuals at sea.”

Mr. Duterte has barred the military from joining naval exercises in the South China Sea to keep a lid on tensions, but critics see it as allegiance to China.

Mr. Villarin said the Philippines and other claimants should sue China before an international tribunal once it enforces its law.

Renato C. de Castro, an international studies professor at the De La Salle University (DLSU), said the Chinese law had killed any plans to come up with a code of conduct in the South China Sea.

Manila should also use its military pact with the United States such as the visiting forces agreement as a way of flexing its military muscles, he said via Zoom. Mr. Duterte should order the Philippine Coast Guard to deploy ships in the area and “raise our flag.”

Presidential Spokesperson Harry L. Roque, Jr. earlier said the Philippines would try to remain friendly to Beijing while protecting the national interest.

Mr. Castro said the government should not sacrifice its territorial rights in exchange for coronavirus vaccines from Chinese drug makers.

“We should not allow them to leverage their vaccines to put us on a defense slip,” he said. “Why should we sacrifice our territories for vaccines with a 60% efficacy rate?”

The Philippines last week filed a diplomatic protest against China. Foreign Affairs Secretary Teodoro L. Locsin, Jr. deemed the passage of the measure a “verbal threat of war.”

“It’s time that we also deploy our coast guard,” Mr. de Castro said, noting that the Philippines had yet to deploy 12 patrol vessels from Japan.

The law passed by the National People’s Congress standing committee of China will allow its coast guard to use “all necessary means” against foreign vessels that threaten them, according to the South China Morning Post.

Mr. de Castro said the Philippines could also use its alliance with the US even if it leads to tensions at sea. The latest Chinese law gives the Philippines more reason to renegotiate the visiting forces agreement (VFA) with the US, he added.

Senator Aquilino L. Pimentel III said the Philippines could work with other claimants for a “coordinated Association of Southeast Asian Nations response,” including speaking with China to prevent “untoward incidents.”

“Form a Department of Foreign Affairs think tank to propose a rule in international law to prohibit the militarization of disputed waters and the use or threat of arms,” the lawmaker, who heads the Senate foreign relations committee, said in a Viber message at the weekend.

Mr. de Castro said China was likely to ignore this. “You don’t need another law because what China would do is continue violating international law.”

The United Nations Permanent Court of Arbitration in 2016 favored the Philippines in a lawsuit that rejected China’s claim to more than 80% of the South China Sea based on its nine-dash line drawn on a 1940s map.

China has rejected the ruling but continues to negotiate with the Philippines and other Southeast Asian nations to come up with a code of conduct. — Kyle Aristophere T. Atienza and Charmaine A. Tadalan