MANILA, Philippines — A threat largely hidden beneath the country’s surrounding waters is drawing increasing concern from Philippine officials, who are warning that submarine cables, power links and offshore energy infrastructure could become targets of sabotage, cyberattacks and so-called gray-zone operations.
The warning was raised during the Department of Foreign Affairs’ Experts’ Forum on Critical International Maritime Infrastructure on September 8, as government agencies pushed for stronger surveillance, legal protections and regional cooperation to protect infrastructure that quietly keeps the Philippine economy running.
The concern extends far beyond the physical cables resting on the seabed.
Submarine telecommunications cables carry more than 99% of international data traffic worldwide, according to the International Telecommunication Union. Any major disruption could therefore affect communications, internet connectivity, financial transactions, businesses and essential government services.
For the Philippines, the vulnerability is particularly significant because of the country’s geography.
The Philippine Domestic Submarine Cable Network spans roughly 2,500 kilometers and connects islands across the archipelago. The country is also linked to the global internet through international submarine cable systems, while offshore energy infrastructure such as the Malampaya pipeline provides another critical subsea connection.
From accidents to deliberate attacks
Philippine officials said the risks facing underwater infrastructure are no longer limited to natural disasters, fishing activity or accidental damage from ships.
Foreign Affairs Undersecretary for Policy Leo Herrera-Lim said the threat environment is expanding to include gray-zone tactics, state-sponsored cyberattacks, physical sabotage and geopolitical tensions.
The Department of Energy has likewise identified three broad areas of vulnerability: physical and climate-related risks, geopolitical and regional threats, and cyber threats.
Energy officials pointed to previous incidents in which ship anchors damaged submarine power cables, illustrating how vulnerable seabed infrastructure can be even without deliberate attacks.
The danger becomes more complicated in contested waters.
DOE Undersecretary Giovanni Carlo Bacordo warned that subsea infrastructure could face covert reconnaissance, physical harassment and unauthorized activity, while increasingly digitalized energy systems could expose remote networks and offshore facilities to cyberattacks.
The legal problem could be just as dangerous
Perhaps the most difficult issue for Manila is not simply detecting a threat — but determining who can legally be held responsible if an attack occurs offshore.
Justice Department Chief State Counsel Dennis Arvin Chan warned that Philippine laws may not adequately address deliberate attacks against submarine cables and pipelines located in the country’s exclusive economic zone or continental shelf.
Within Philippine territorial waters and archipelagic waters, damage to such infrastructure can generally be addressed under existing laws governing property damage.
But the legal picture becomes considerably more complicated farther offshore.
Under the United Nations Convention on the Law of the Sea, the Philippines exercises sovereign rights in its exclusive economic zone rather than full sovereignty over those waters. That distinction can create jurisdictional challenges when a foreign vessel deliberately damages infrastructure on the seabed.
Chan raised a hypothetical scenario involving a foreign fishing vessel intentionally dragging an anchor across the seabed to destroy a cable or pipeline — potentially while acting on behalf of another state.
That scenario could expose a significant gap between the ability to detect an attack and the ability to prosecute those responsible.
Manila moves to close the loophole
The DOJ is now working on measures intended to strengthen the country’s legal defenses.
These include developing implementing rules for the Philippine Maritime Zones Act and the Philippine Archipelagic Sea Lanes Act, while examining how international maritime law can be incorporated into Philippine legislation.
The government is also considering changes to provisions concerning piracy and malicious mischief so that attacks against submarine cables and pipelines are more explicitly covered.
The DOJ has additionally moved to institutionalize a permanent Maritime Advisory and Legal Action Unit that can help develop legislation, advise government agencies and address emerging legal challenges involving the country’s maritime domain.
The Philippines is also improving surveillance
Legal reforms are being accompanied by efforts to improve Manila’s ability to see what is happening beneath and around its waters.
In June, the Philippines was set to receive four U.S.-made Triton autonomous surface and underwater vehicles for maritime surveillance. The systems can operate on the surface and underwater and are designed to support persistent monitoring of maritime activity, including potential threats to subsea infrastructure.
The development comes as Philippine authorities increasingly emphasize maritime domain awareness amid continuing tensions in the West Philippine Sea.
Reuters reported this week that Defense Secretary Gilberto Teodoro continues to view China’s growing influence and activities in the region as a major strategic concern, while Manila expands security cooperation with the United States and other partners.
However, officials at the September 8 forum were careful not to accuse any particular country of planning or carrying out attacks against Philippine undersea infrastructure.
That distinction is important.
The warning is about the growing vulnerability of critical infrastructure and the need to prepare before a serious incident occurs, rather than confirmation that a major subsea attack has already happened.
Why the stakes are so high
A damaged submarine cable may be invisible from the surface, but its consequences can quickly become visible on land.
The ITU says submarine telecommunications cables are the backbone of global digital connectivity and carry more than 99% of the world’s data traffic. The organization has warned that these systems face physical risks, natural hazards, repair delays and increasing dependence on a limited number of cable routes.
For an archipelagic country like the Philippines, the challenge is even more complicated.
Thousands of kilometers of seabed infrastructure connect the country’s islands and link the Philippine economy to the rest of the world.
And if an adversary were ever able to exploit that vulnerability deliberately, the impact would not necessarily be limited to the ocean.
It could potentially reach the internet, communications, energy supply, businesses and government operations onshore.
That is why Philippine officials are now pushing the issue beyond maritime security and into the broader question of national resilience.
With the Philippines chairing ASEAN in 2026, Foreign Affairs Secretary Ma. Theresa Lazaro said the protection of critical maritime infrastructure should also be elevated in regional forums, including ASEAN, the East Asia Summit and the ASEAN Regional Forum.
For Manila, the message is increasingly clear: the next major security threat may not always arrive visibly on the horizon.
Some of the most important battles for the country’s security and connectivity could begin hundreds of meters below the sea.
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