Protecting Subsea Cables: Detect to Deter, Sue to Secure

Commentary by Joel Coito

Published December 12, 2025

Subsea cables are vital to transmitting data and connecting international markets. Over 95 percent of data, and $10 trillion in daily financial transactions, travels globally across 1.5 million kilometers of submarine cables. The economic import and utility of subsea cables for both governments and private citizens make it an attractive, and vulnerable, target for state and nonstate actors, something previous CSIS work has called the "soft underbelly of the world economy." High-profile incidents, including the sabotage of the Nord Stream 1 and 2 natural gas pipelines and separate cable damage incidents in the Baltic Sea caused by dragging anchors of the Chinese-owned vessels Newnew Polar Bear and Yi Peng 3, have highlighted this vulnerability in dramatic fashion. Government leaders are taking notice, and the need for greater cable security is evidenced by NATO's formation of a Critical Undersea Infrastructure Network and a Maritime Centre for the Security of Critical Undersea Infrastructure. At the same time, technology giants Amazon, Google, Meta, and Microsoft have made substantial investments in subsea cable projects to increase redundancy and meet connectivity and capacity demands attendant to record growth in data center and artificial intelligence (AI) infrastructure.

A host of challenges to subsea cable protection persist. First, most physical damage to undersea cables is accidental: usually the result of anchoring or commercial fishing, and sometimes due to natural hazards such as earthquakes or tsunamis. Where there is evidence of intentional damage-cable cutting or attacking cable landing stations-commentators have lamented weak peacetime protections provided by the existing international treaty regime, "woefully inadequate" penalties, and prosecutorial "gaps" that have allowed bad actors to escape meaningful accountability.

Further, international treaties governing undersea cables are dated. The flagship 1884 treaty governing submarine cables, the Convention for the Protection of Submarine Telegraph Cables could benefit from amendments aimed at better calibrating penalties to the harms caused by intentional cable damage. But major powers including China and Russia-both of which have been widely accused of intentionally damaging cables in recent years-are unlikely to participate in such a negotiation or abide by an updated treaty regime. Even when political will exists, the machinery of international negotiation turns slowly and often requires national legislation to have practical effect.

Accordingly, the best way to protect subsea cables in the near term is to shine a light on the activities of bad actors. This can be accomplished by government and private companies acting now, even in the absence of a new treaty or national legislation. While the 1884 convention has stood the test of time, more tools are needed to achieve deterrence: reputational damage to vessel operators, naming and shaming of responsible actors and delinquent flag states, and embedded financial penalties when marine insurance carriers drop suspect vessels or provide coverage only at a steep premium. But how? Using the very tools that are driving a need for greater numbers of undersea cables-AI, quantum applications, and advanced sensors-to build a real-time picture of the maritime domain and eliminate plausible deniability by bad actors. Private remedies are also underutilized. Where intentional submarine cable damage occurs, cable owners should seek damages and declaratory judgments of illegality to foster deterrence.

Figure 1: World Submarine Cable Map

Source: TeleGeography, "Submarine Cable Map," https://www.submarinecablemap.com/.

Shining a Light: Deterrence by Detection

A perennial challenge in maritime law enforcement is the tyranny of distance. Traditionally, countries seek to achieve maritime domain awareness of vast oceans by combining the inputs of individual ships, aircraft, and intelligence. A costly proposition, this is largely the realm of wealthy countries with the most capable naval forces and intelligence apparatus. But leading-edge technologies are providing both public and private sectors with tools to monitor expansive maritime spaces at reasonable cost. As David Brewster of the National Security College at Australian National University has observed, these "new technologies provide the opportunity to democratize access to information" and help smaller countries better monitor their waters.

The democratization of maritime data fosters an innovative private market. Low-cost commercial satellites have "brought much of the oceans under regular observation," and once-impenetrable data sets now feed real-time displays through AI, machine learning, and predictive analytics. Some companies crowdsource Automatic Identification System (AIS) data (though a recent thoughtful analysis notes the vulnerability of AIS's open architecture to spoofing and hacking, and Chinese vessels have repeatedly evaded AIS) or pool data from networks of enrolled vessels to support cutting edge maritime intelligence services.

The nonprofit sector has also played a key role in developing ocean protection technologies. Skylight, based at Ai2, a nonprofit organization focused on conducting AI activities for the common good, cues satellite imagery to suspicious vessel behavior and leverages AI tools to support maritime compliance and enforcement. Fellow nonprofit Global Fishing Watch utilizes open-access technology, data sets, and map visualizations to create actionable information to help stop illicit maritime activity, including unlawful fishing and secret dredging. These same tools can be used to quickly identify vessel anomalies indicative of subsea cable sabotage, including extended loitering over critical infrastructure, "dark" operations with AIS turned off, and deployment of specialized equipment near submarine cables. Both private and public sectors can thus spotlight attempted subsea cable attacks and foster "deterrence by detection."

While governments no longer have a monopoly on maritime information tools, they will remain a primary customer for, and driver of, such technology. For example, the U.S. Coast Guard Futures Development and Integration Directorate recently released a Request for Information seeking to assess and leverage leading-edge technologies to shift the traditional maritime domain awareness paradigm to maritime domain dominance (MDD). The difference is more than semantic: The Coast Guard's vision of MDD would couple traditional maritime inputs from cutters, small boats, and aircraft with all-domain sensors (air, space, surface, and shore) and leverage "revolutionary technologies" to provide a comprehensive threat picture to operators. What the Coast Guard calls the "detect-to-act pipeline" is precisely the real-time threat detection capability necessary to stop subsea cable damage-intentional or not-before it happens.

Nor should new technologies displace existing whole-of-government or government-to-government information sharing. In the United States, the Maritime Operational Threat Response process remains a proven, effective coordination mechanism for the U.S. interagency to respond to complex maritime threats including attempts to destroy undersea infrastructure. Similarly, the European Union's Critical Maritime Routes capacity-building program facilitates interagency coordination and information sharing among both civilian and military entities. These information-sharing mechanisms enhance maritime security, and efforts are underway to modernize and better integrate intelligence and other data to bolster detection and enforcement outcomes. Finally, continued government demonstration of exquisite intelligence capabilities, such as the foreign signals intelligence collection that led to the finding of Osama Bin Laden, should give pause to state and nonstate actors seeking to sponsor or carry out undersea cable attacks.

Sue to Secure: Deterrence by Judgement

Better detection of subsea cable attacks is necessary-but not sufficient-for comprehensive cable protection. As stated in previous CSIS research, deterrence by punishment has its own role to play. At first glance, U.S. law provides sparse punishment options for willfully damaging a submarine cable: a misdemeanor offense, up to two years in jail, and a fine up to $5,000. But it also provides for private remedies and explicitly notes that criminal punishments are not a bar to a suit for damages. Much ink has been spilled documenting the various challenges of punishing subsea cable attacks, including dated international instruments, consortium cable ownership, and cables that cross multiple jurisdictions. But private remedies are an underutilized tool to deter bad actors, and it is time for cable owners to adopt a bias for action in the courtroom.

Google provides an instructive example. In November 2025, the tech giant filed a lawsuit in federal court against "Lighthouse," a criminal organization based in China that provides phishing software and support to online fraudsters. Google alleges Lighthouse created fake websites that included Google logos and targeted victims in over 120 countries. Google filed the lawsuit despite not knowing the identities of the defendants, referred to as "Does 1-25," who remain in China. In a recent interview with NPR, Google General Counsel Halimah DeLaine Prado candidly conceded the lawsuit's goal was "deterrence" rather than going to trial-specifically, a declaratory judgement that the fraudulent acts were illegal. In short, Google seeks (1) private remedies against foreign defendants, (2) potentially beyond the jurisdictional reach of U.S. courts, for (3) "immeasurable" damages suffered by diffuse and geographically diverse victims in order to (4) deter rather than convict the offenders. While online fraud is substantively different than subsea cable sabotage, the four core case elements listed above hold for both. Google's lawsuit provides a roadmap for cable owners seeking to deter subsea cable damage and increase public awareness of the issue, even if those bad actors never see a U.S. courtroom.

In fact, the jurisdictional case for civil liability may be stronger in the context of submarine cables. Professor James Kraska and Commander Elizabeth Hutton of the U.S. Naval War College have persuasively argued that the doctrine of constructive presence-a well-established doctrine of jurisdiction in international maritime law long used in salvage and "hot pursuit" cases-should also apply in the event of intentional subsea cable damage. The thrust of this doctrine gives coastal states redress against vessels committing unlawful acts in international waters that create concrete harms for the coastal state, and thwarts bad actors' attempts to evade jurisdiction by avoiding sovereign waters. Subsea cable owners should pursue this line of reasoning, which if successful would allow a court to exert jurisdiction over a cable-cutting vessel in international waters because its nefarious action "is materially and directly linked to the damage or harm of portions of the [critical underwater infrastructure] that physically lie within the territorial sea of that connecting coastal State."

There are also promising legislative and regulatory developments to better protect subsea cables and bolster legal accountability for intentional damage. In September 2025, the U.S. House of Representatives passed the Undersea Cable Control Act, which seeks to prevent foreign adversaries from acquiring items needed to support the construction, maintenance, or operation of undersea cable projects. Two months later, the Strategic Subsea Cables Act of 2025 was introduced in the Senate, which would bolster punishments for subsea cable damage and require the president to impose sanctions against foreign individuals who have intentionally damaged subsea fiber-optic cables. These legislative developments, coupled with the Federal Communication Commission's national security-focused rulemaking on submarine cable landing licensing, highlight growing political will to better prevent and punish intentional cable damage; laudable and timely efforts. Further protecting subsea infrastructure should be a bipartisan priority.

Conclusion

A subsea cable attack can instantly disrupt global communications and economic activity. Though rare, sabotage attacks on subsea cables are an attractive hybrid tactic China, Russia, and other state and nonstate actors can wield to impose economic costs, disrupt services, and sow popular unrest. Governments, private companies, and the nonprofit sector should leverage cutting-edge technologies that have democratized maritime data, including AI, predictive analytics, and cued satellite imagery, to detect and deter would-be saboteurs. Deterrence by detection eliminates plausible deniability and imposes real costs ranging from reputational damage to elevated insurance premiums. Moreover, suits against those intentionally damaging subsea cables are an underutilized deterrence mechanism. Accordingly, cable owners should aggressively pursue remedies in the courtroom. By seeking damages and declaratory judgements of illegality, these owners shine a brighter light on the threat of submarine cable damage even where a defendant cannot be brought to U.S. court. There are promising legislative and regulatory efforts underway in the United States to reduce threats to subsea cables and sanction bad actors. In the meantime, detecting to deter and suing to secure are tools that can and should be brought to bear.

Commander Joel Coito is a military fellow in the Defense and Security Department at the Center for Strategic and International Studies (CSIS) in Washington, D.C.

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