MANILA (UPDATE) — China has opposed a Philippines-led push for a review of its 70-year-old defense treaty with the United States, Manila's defense chief said on Thursday, concerned that it could be seen in Beijing as an effort to contain its rise.

The Philippines is keen to amend the 1951 Mutual Defense Treaty (MDT) to make clear the extent to which the United States would protect and defend its ally should it come under attack.

• PH, US reaffirm committment to Mutual Defense Treaty

At an event to mark the MDT's 70th anniversary, Defense Secretary Delfin Lorenzana said he had been urged by a former Chinese diplomat to back off.

"While the US welcomes the idea of revisiting the MDT, an outside party does not," he said.

"The former Chinese ambassador came to me and said: 'Please do not touch the MDT. Leave it as it is,'" said Lorenzana.

He later clarified the conversation took place in 2018.

"It did surprise me. I asked him why? He said any attempt to revise the MDT would be construed by the Chinese government as [an] act to contain the rise of China," Lorenzana told Reuters.

Asked how he responded, Lorenzana said: "I just looked at him and smiled."

There was no immediate comment from the Chinese embassy in Manila.

The push for clarity on Washington's commitment comes amid a rapid buildup of Chinese maritime assets in contested areas of the South China Sea, including what the Philippines says is a militia disguised as a massive fishing fleet near Beijing's militarized manmade islands.

The Philippines has filed dozens of diplomatic protests about the militia and announced it would send another on Thursday.

• US asserts Mutual Defense Treaty applies to South China Sea amid tensions

The Philippine-US alliance has existed for decades, with a rotating presence of US troops for joint exercises, intelligence exchanges and hardware transfers.

Lorenzana said it was clear that strengthening the MDT was not in China's interests.

"The Chinese, having embedded themselves with their artificial islands, are not in a hurry for any resolution," he told the forum.

"It knew that any aggression it takes will trigger the MDT."

A maritime law expert, meanwhile, sees no need to renegotiate the 70-year old treaty, saying it would be more useful to come up with operational guidelines of the treaty similar to what the US and Japan have done on their own defense pact.

Jay Batongbacal of the University of the Philippines Institute for Maritime Affairs and Law of the Sea said it would not be practical to come up with a new treaty as it would be difficult to come up with enough votes for it to pass in Congress given “the highly contentious nature of politics” in both countries.

He pointed out the MDT is “very broadly worded” that it can already “encompass so many things.”

“What is needed, instead of renegotiating this treaty, is to come up with the appropriate operational guidelines which contain the actual and practical implementation of this age-old treaty," he said.

The 1951 MDT states that “an armed attack on either of the parties is deemed to include an armed attack on the metropolitan territory of either of the parties or on the island territories under its jurisdiction in the Pacific Ocean, its armed forces, public vessels or aircraft in the Pacific.”

Former US State Secretary Mike Pompeo first categorically stated in 2019 that the South China Sea is covered by the MDT.

The Trump and Biden administrations also called on Beijing to abide by the 2016 arbitral ruling that invalidated its claims in the South China Sea.

• Palace says 'no one can diminish' PH arbitral win that China calls 'wastepaper'

Biden administration officials welcomed the recent decision of President Rodrigo Duterte to recall the termination of the Visiting Forces Agreement, which provides the legal framework under which US troops can operate on a rotational basis in the Philippines.

• US Embassy lauds PH decision to restore VFA, says pact strengthens security in region

International studies professor Renato de Castro, meanwhile, said voters should avoid electing a “defeatist candidate” for president in the 2022 national elections, stressing the need for government to come up with a national security strategy delineating the country’s plan to defend its national interests.

Duterte last year said he was "inutile" and "cannot do anything" against Beijing's pursuit of territory and resources in the South China Sea.

• Duterte says he is ‘inutile, cannot do anything’ against China sea aggression

“We should avoid a defeatist candidate, somebody who would say, 'China is too powerful, China is too big, there is no point in challenging China.' We have heard that in the last 6 years. We cannot afford another,” De Castro said.

“We have to protect the maritime domain because this is where the threat would come from."

—With a report from Willard Cheng, ABS-CBN News

RELATED VIDEO

Watch more in iWantv or TFC.tv