The Philippines has filed another diplomatic protest against China over its warships passing Philippine waters without informing the country's authorities, Foreign Affairs Secretary Teodoro Locsin Jr. said Thursday.

• 5 more Chinese warships sailed in PH waters without informing Manila

"They just fired off, that's it. I am afraid that's all I can say,” Locsin told reporters but declined to disclose details.

"You know how I feel about speaking to the civilian media. I speak only to the Army, really. That’s the best. I already described my foreign policy as the fist and iron glove of the Armed Forces so we work hand-in-hand with the military."

Asked if President Duterte is pushing through with his trip to China, Locsin said: "I don’t see why not."

He said of the visit’s agenda, “We’re working on that right now.”

Locsin earlier this week told his department's Office of Asia and Pacific Affairs to "drop the diplomatic crap" after Defense Secretary Delfin Lorenzana questioned the unannounced passage of 9 Chinese warships in Sibutu Strait in the Philippines' southern tip.

@DFAPHL @ASPAC fire diplomatic protest over Chinese warship; drop the diplomatic crap; say it is ours period; they're trespassing. If we did it already fire another. We won't run out. & don't wait for formal intel. This is the Secretary of National Defense no less. Fire at will.

— Teddy Locsin Jr. (@teddyboylocsin) August 19, 2019

The Philippines earlier protested the passage of Chinese warships through Sibutu Strait without prior clearance, and the swarm of 113 Chinese vessels around Filipino-occupied Pag-asa Island.

• Philippines protests China's moves in Sibutu Strait, Pag-asa Island

Under the United Nations Convention on the Law of the Sea, any foreign vessel may be allowed to cross a coastal state’s territorial waters without notifying the state if they are conducting innocent passage, or movement in a straight path heading back out to sea.

Defense Secretary Delfin Lorenzana said the Chinese warships' passage were "not so innocent anymore."

“I think it's not innocent anymore, dahil palagi na 'yan eh. Palagi na 'yang ginagawa eh. 'Saka why don’t they inform us? Ano ba 'yung 'huy, daan kami, makikiraan po.' Ganun lang naman 'yun sa'tin diba? Why the secrecy?” he said.

• Why the secrecy? Lorenzana flags passage of 9 Chinese warships through PH waters

In his speech during the opening of the ceremony of the 7th Biennial Conference of the Asian Society of International Law, Locsin said if only treaty obligations under UNCLOS were respected, “there would be less animosity with its greater likelihood of conflict.”

He added: "If only the greatest power on earth led by the example of subscribing to UNCLOS, it would be a safer world.”

He urged the participants of the conference to discuss if "pacta sunt servanda" or the duty to perform one’s obligations in international law "is still relevant when more states refuse to recognize let alone carry out judicial or arbitral awards they lost fairly and legally."