UNDERWATER WARFARE
Underwater warfare
As the world becomes ever more interconnected, Tanya Vatsa highlights how submarine cables are emerging as a new geopolitical battlefield
In today’s hyper connected world, the arteries of global communication run silently beneath our oceans. These submarine cables, though hidden from view, have become pivotal battlegrounds in the shadow wars of geopolitics, responsible for carrying 95 per cent of international data traffic.
Recent incidents, from the South China Sea to the Red Sea, have fuelled speculation that these undersea lifelines are being deliberately targeted as part of broader strategic manoeuvres. With China emerging as a primary suspect in many of these disruptions, the implications of such attacks stretch far beyond connectivity issues – they strike at the very core of economic stability, financial markets and military readiness.
Taiwan has borne the brunt of repeated undersea cable disruptions, many of which are suspected to have originated from Chinese vessels operating under ambiguous circumstances. In January 2025, Taiwanese authorities detained the Hongtai, a Togolese-flagged cargo ship manned by a Chinese crew, after it was linked to the severing of a key undersea cable connecting Taiwan to the Penghu archipelago. This incident, the latest in a string of similar occurrences, is being scrutinised as a potential act of grey-zone warfare – strategic yet deniable provocations designed to test Taiwan’s resilience without crossing the threshold into open conflict.
Earlier, in February 2023, two submarine cables connecting Taiwan’s Matsu Islands to the main island were cut, plunging the region into near-total digital isolation. The responsible vessels, both Chinese-owned, conveniently disappeared before further investigations could be conducted. The financial impact was immediate – businesses relying on cloud-based services faced millions in losses, while emergency services struggled to maintain critical communications.
The strategic importance of submarine cables extends far beyond the Indo-Pacific. The Red Sea, a critical conduit for global trade and data transfer, has also become a hotspot for cable disruptions, with devastating consequences for the world economy. In February 2024, Houthi militants attacked a commercial vessel in the Red Sea, inadvertently damaging four undersea cables responsible for carrying data traffic between Europe, Asia and Africa. The result was widespread latency spikes, slowed financial transactions, and connectivity issues across multiple continents. Approximately 25 per cent of data traffic in the region was affected, disrupting critical business operations and increasing insurance premiums for undersea cable repairs.
The economic cost of such attacks is staggering. The February 2024 Red Sea disruptions alone resulted in over $50 million in immediate repair costs. More significantly, the disruption to global supply chains, financial networks and e-commerce transactions is estimated to have caused indirect losses amounting to hundreds of millions of dollars. Given that nearly 80 per cent of Asia’s westward data traffic flows through these routes, prolonged instability in the Red Sea could pose a serious risk to the global digital economy.
The strategic importance of submarine cables extends far beyond the Indo-Pacific
This emerging pattern of submarine cable sabotage is not confined to Asia or the Middle East. In November 2024, disruptions in the Baltic Sea added another layer to this growing crisis. A Chinese-registered bulk carrier, Yi Peng 3, was investigated after its erratic movements coincided with multiple data cable disruptions between Finland and Germany. The vessel’s Automatic Identification System (AIS) had been turned off for extended periods, and subsequent inspections revealed a damaged anchor – suggesting it had been intentionally dragged along the seabed. While conclusive proof remains elusive, European security agencies are increasingly viewing such incidents as strategic acts rather than maritime accidents.
What makes submarine cables attractive targets? Their destruction is highly disruptive yet difficult to attribute definitively – perfect for states looking to exert influence while maintaining plausible deniability. By targeting these digital arteries, adversaries can cripple financial markets, disrupt high-frequency trading and compromise military communication – all without firing a single shot.
This emerging pattern of submarine cable sabotage is not confined to Asia or the Middle East
China’s increasing assertiveness in the digital domain has only reinforced fears that submarine cables could become primary targets in an escalating strategic competition. Analysts warn that deliberate sabotage could be used as a means to pressure adversaries, undermine economic stability, or even serve as a prelude to larger military operations. The growing number of incidents – from Taiwan’s severed cables to the Baltic Sea’s suspicious disruptions – suggests that a new frontier of digital warfare is already unfolding beneath the ocean’s surface.
Governments and private stakeholders are now scrambling to mitigate the risks posed by undersea cable sabotage. Taiwan has begun deploying additional surveillance mechanisms to monitor maritime traffic near its critical infrastructure, blacklisting numerous Chinese-owned vessels operating under flags of convenience. Meanwhile, the US and its allies are investing in alternative routing for trans-Pacific cables to bypass high-risk zones, instead favouring connections through allied territories such as Japan, Australia and Pacific island nations. Projects like the Bifrost and Echo cables prioritise landings in Indonesia, the Philippines and Guam, reducing exposure to potential Chinese interference. However, experts warn that these measures might not be enough in the face of increasingly sophisticated threats.
The international community must prioritise the security of undersea infrastructure through collective action – strengthening monitoring systems, improving repair capabilities and holding perpetrators accountable. In an era where economic dominance is dictated by the control of data, the battle over submarine cables may very well shape the foundation of the next geopolitical re-shuffle.
The silent war beneath the waves is already underway. The question is, how prepared is the world to defend its invisible digital lifelines?
Tanya Vatsa is currently the Geopolitical and Predictive Intelligence specialist at Inquest Advisories in India, as well as Editor at the Journal of Indo-Pacific Affairs, Dept of Defence, United States of America. She completed her Master’s in Legal Studies at the University of Edinburgh after obtaining a law degree from Lucknow’s National Law University, India