On February 25 2025, Taiwan's coast guard detained the Hong Tai 168, a Chinese-owned freighter, under suspicion of allegedly severing an undersea communications cable off its western coast. This incident is suspected to be part of China's "grey zone" tactics — a term and strategy loosely defined as hostile actions below the threshold of war in war studies parlance.

The incident has disrupted cables that qualify as critical national telecommunication infrastructure connected to Taiwan's Penghu Islands in the second such incident in two months. However thanks to the fact that other cables remained intact there was no significant service outage for the people on the islands in the latest incident.

According to a report in Deutsche Welle, the vessel, registered under a Togolese flag but crewed entirely by Chinese nationals, was found near the damaged cable and had ignored multiple warnings from Taiwanese authorities.

This event highlights a broader trend in the Indo-Pacific region as well as around the world — the persistent ambiguity surrounding such incidents allows state actors to interfere with critical infrastructure while maintaining plausible deniability, thereby avoiding diplomatic or military escalation.

A similar pattern has emerged in another major maritime zone of commerce, the Baltic Sea.

According to a December 2024 report by the Carnegie Endowment for International Peace, in October 2023, the Hong Kong–flagged, Chinese-registered vessel NewNew Polar Bear was implicated in damaging two submarine telecom cables and a gas pipeline in the Baltic sea. A year later, in November 2024, another Chinese cargo ship, Yi Peng 3, allegedly severed two submarine communications cables connecting Germany to Finland and Lithuania to Sweden. These incidents have raised suspicions of deliberate sabotage, yet definitive attribution remains elusive.

A January 2025 report by NBC News notes that these cases, often involving vessels operating under “flags of convenience” - meaning vessels belonging to states that don’t regulate their affiliated shipping as stringently, demonstrate how state-aligned actors can conduct disruptive operations without clear accountability, thereby reducing the risk of retaliation.

Furthermore the series of incidents in the Baltic sea could have served as a test run for China to gauge the response time and attribution capabilities of states with arguably the best maritime security capabilities globally, before committing to a pattern of sabotage Beijing could get away with closer to home.

The reluctance or inability of littoral nations in the Baltic sea to conclusively attribute these acts to state sponsored entities has set a concerning precedent. This lack of clear attribution hampers immediate response efforts and emboldens state-aligned actors to replicate such tactics in other strategic regions, notably the Indo-Pacific.

The recent incidents off Taiwan's coast exemplify this spillover effect, demonstrating the urgent need for coordinated international efforts to safeguard critical undersea infrastructure.

According to a 2017 report by Policy Exchange, submarine cables are essential to global communications, carrying approximately 97% of international data traffic and supporting financial transactions worth an estimated $10 trillion per day. Despite their immense strategic and economic importance, these cables remain highly vulnerable to both accidental and deliberate damage.

According to a 2020 report by the Takshashila Institution in India, repairing these cables is a complex and costly endeavor, often requiring specialised ships and extended operational timelines. The ease with which they can be targeted underscores the pressing need for enhanced security measures.

The Indo-Pacific has historically been shaped by territorial disputes and competition over fishing rights, but the recent undersea cable disruptions indicate an evolving security landscape. Maritime sabotage, particularly through "grey zone" operations, exploits gaps in international law and maritime surveillance, making it difficult for affected nations to respond effectively.

To address this emerging threat, a collaborative approach is necessary. The Quadrilateral Security Dialogue (Quad), comprising the US, Japan, India, and Australia, is well-positioned to lead efforts in safeguarding undersea infrastructure.

Establishing a dedicated multinational constabulary force focused on undersea cable protection could enhance maritime domain awareness, improve coordination in rapid response efforts, and deter future sabotage attempts through a visible and proactive presence. Several additional key measures would also be essential to such an initiative.

According to the analysis by the Takshashila Institution, enhanced surveillance and monitoring capabilities, including the deployment of advanced maritime patrol aircraft, unmanned systems, and electronic intelligence assets, would improve real-time detection of suspicious activities along critical cable routes.

Additionally, strengthening legal and policy frameworks among Quad nations could facilitate coordinated responses, information sharing, and joint operational measures. Private sector engagement, particularly with telecommunications companies and undersea cable operators, would be crucial in developing security protocols, conducting vulnerability assessments, and ensuring rapid repair capabilities in the event of disruptions.

Furthermore, regional capacity building efforts would empower smaller Indo-Pacific nations with the tools and expertise needed to protect their own maritime infrastructure, contributing to a broader security architecture. Implementing these measures would not only fortify global communications networks but also serve as a deterrent against further acts of sabotage.

The incidents in the Baltic Sea and off Taiwan’s coast reveal a growing strategic vulnerability that requires immediate attention. The exploitation of plausible deniability in maritime sabotage erodes international norms and endangers the integrity of critical infrastructure. Addressing this challenge through multilateral cooperation, improved surveillance, and decisive countermeasures will be essential in preventing future attacks and ensuring the resilience of global communications.

The Quad nations, leveraging their collective capabilities, have the opportunity to lead the development of robust countermeasures against maritime sabotage. By prioritising undersea infrastructure security, they can reinforce regional stability, deter covert aggression, and uphold the rules-based international order in the face of evolving threats.