The government is drawing up guidelines for joint patrols with allies in the West Philippine Sea (WPS) in the face of increasingly aggressive behavior by China in the disputed waters of the South China Sea.

Operational details, including the possible engagement of other regional partners, will be part of talks between the Philippines and the United States, which have a mutual defense treaty, the Department of Foreign Affairs (DFA) said Thursday.

Last month, defense officials said they were considering joint patrols with the United States, Japan and Australia, but the DFA did not provide any details this week on which countries would take part in them.

The DFA said the Mutual Defense Board-Security Engagement Board (MDB-SEB) mechanism with the US draws up activities that will be undertaken by the two allies.

Despite a decision by the Permanent Court of Arbitration in favor of Manila, Beijing still insists it has sovereignty over the West Philippine Sea, which is well within the Philippines’ exclusive economic zone (EEZ).

In a recent visit to the country, US Defense Secretary Lloyd AustinIII reiterated Washington’s commitment to help defend the Philippines, a long-time treaty ally, against aggression after a Chinese coast guard vessel pointed a military-grade laser at a passing Philippine supply ship near Ayungin Shoal on Feb. 6.

The laser-beaming incident off Ayungin — also known by its international name Second Thomas Shoal — caused temporary blindness to some of the Filipino crew and prompted Manila to file a strongly worded diplomatic protest.

Australian Defense Minister Richard Marles, who also visited Manila last month, announced at a press conference that they are eyeing joint patrols with the Philippines in the disputed waters.

Apart from the US, only Australia has an existing defense pact with the Philippines that allows joint military exercises in the country.

The Philippine Constitution bans foreign bases and permanent presence of foreign troops and their engagement in local combat.

China, which considers the sea disputes as a purely Asian issue, is opposed to any foreign intervention, particularly from the US.

In a talk with troops before the Visayas Command in Cebu earlier this week, President Ferdinand Marcos Jr. said the mission of the Armed Forces of the Philippines has evolved amid the “most difficult and complicated” issue on the South China Sea and the “intensification of the competition of superpowers.”

Marcos said the military must adjust accordingly to the changing security situation.

“For many, many years, we were able to maintain that peace and maintain that understanding with all of our neighbors. Now things have begun to change and we must adjust accordingly,” he said.

The Philippine Coast Guard said Monday it would make public all incidents of Chinese incursions in the West Philippine Sea.

PCG adviser for maritime security Commodore Jay Tarriela said this would compel China to react and acknowledge its actions.

Earlier, Tarriela said at least 30 Chinese maritime militia and coast guard vessels that were spotted earlier in Ayungin and Sabina Shoals remain inside the country’s maritime domain.

He said it is now up to the Department of Foreign Affairs to decide on whether to lodge another diplomatic protest over the presence of Chinese vessels inside the country’s exclusive economic zone.

Beijing claims nearly the entire South China Sea and has refused to acknowledge a 2016 arbitral ruling invalidating its nine-dash-line maritime claim.