By Liz Lagniton | 2026-01-16

The Philippines is developing measures to secure submarine cables that authorities found to have been tapped in Philippine waters, affecting communications and national security.

The undersea cables that the Philippines aims to secure crisscross routes linking Southeast Asia with major data hubs in the United States, India and Hong Kong and carry most international internet traffic.

While public reporting remains limited, cable-tapping cases documented elsewhere could pose similar risks in Philippine waters, Rear Adm. Roy Vincent Trinidad, the Philippine navy's spokesman for the West Philippine Sea (WPS), told Defense News on January 5.

The WPS is Manila's term for the part of the South China Sea inside the Philippines' Exclusive Economic Zone.

The navy will take the lead in protecting undersea infrastructure and is examining ways to expand monitoring of subsea cables, including collecting imagery of seabed terrain to track changes over time, Trinidad said.

"It is still in the exploratory stages, but we have been conducting exercises on this with other navies, especially with our defense treaty ally, the United States," he added.

'Gray zone' concerns

Security officials and analysts warn of rising Chinese "gray zone" activity -- covert actions that stop short of open war. Because undersea infrastructure is difficult to monitor, these attacks are easy to carry out and hard to prove.

Beyond the risk of physical damage, Philippine defense officials have raised concerns that the Chinese could intercept or manipulate data passing through undersea cables. There are "ways to listen" to what cables are carrying and enemies could "tap into those cables," said Trinidad.

Meanwhile, fishermen and naval patrols have found unclaimed autonomous underwater devices in Philippine waters, some bearing Chinese markings, and naval officials said forensic analysis of one device showed it had transmitted data to a private firm in China. The drones collect dual-use information that can support benign research but can also help Chinese intelligence agencies map maritime mobility corridors for military purposes, say analysts.

In 2025, China denied allegations of espionage, and the Chinese embassy in Manila at the time described claims involving sleeper agents and intelligence operations as "baseless speculation and accusation."

Lessons from Europe

The Philippines' push reflects lessons from Europe after repeated disruptions by Russia of pipelines and undersea cables in the Baltic and North seas, Paris Dauphine University geopolitics professor Arnaud Leveau told the South China Morning Post.

Investments in monitoring and attribution along key transit routes raise the cost and risk of covert interference, said Leveau, adding that a similar shift is emerging in Southeast Asia as mid-level powers move to secure strategic infrastructure.

Stronger undersea resilience can support regional stability and help ensure Indo-Pacific connectivity is not "quietly weaponized," he said, adding that countries should treat cables as strategic infrastructure requiring whole-government and whole-alliance cooperation.

Challenges in the underwater domain mirror broader concerns involving espionage and infrastructure security, Philippine lawmakers and security officials say. In 2024, the Philippine military barred its personnel from using Chinese social media apps.

Chinese spying on US, Philippine military

Meanwhile, courts are handling cases involving Chinese and Filipino nationals accused of surveilling military installations and US naval vessels, including ships docking at Subic Bay, officials say. Undersea cables, along with satellites, data centers and repair logistics, form a critical but largely unseen layer of the digital economy, and disruptions could affect communications, financial services and government operations, say analysts.

The Philippines is positioning itself as a regional hub for technology and business process outsourcing, and officials and analysts have said reliable connectivity and cable repair are increasingly strategic as Manila prepares to chair the Association of Southeast Asian Nations in 2026.

While the Philippine navy has not disclosed specific platforms or timelines, cooperation with the United States and other partners is helping to build undersea awareness and foundational capabilities, said Trinidad.