Risk Beneath the Waves: Safeguarding Subsea Cables for a Secure Global Network

Cable damage can easily escalate into national security threats. The design and structure of a cable network can introduce systemic risk, as a single incident may disconnect an entire small country from global communications or cause significant delays.

This vulnerability is especially relevant for countries such as small nations or island states that lack redundancy (i.e., spare capacity) in their networks and for which building additional cables is not commercially viable for the private sector or not feasible due to space constraints for cables to land. Furthermore, if cables are concentrated in a particular area due to limited space or routing options, these risks are magnified, as it is easy to damage several cables at one time.

For example, when Taiwan's Matsu Islands experienced cable cuts in February 2023, its residents were plunged into near-total digital isolation. Island residents relied on microwave radio transmission to send small amounts of data.

Because subsea cables carry all types of information, including sensitive data and governmental communications, policymakers are increasingly particular about the vendors who build and repair these cables, as well as the technology within landing stations. Some in government agencies fear that components of submarine line terminal equipment-used to translate the optical signals flowing through the subsea cables into readable data-could clandestinely siphon off information for a bad actor. Private sector experts have been dismissive of the idea, however, noting the computational infeasibility of grabbing such massive sums of encrypted data and using it for any sort of useful espionage purposes.

Finally, malign actors could intentionally target maritime infrastructure as a gray zone tactic to cause societal, economic, or security disruptions. Although these types of cuts are rare and difficult to prove, they invite diplomatic or even military crises in tense geopolitical environments. Of course, in an active wartime scenario, communication infrastructure such as subsea cables may be among the first targets to be destroyed, as has been the case since World War I, when England's opening action was to cut Germany's submarine telegram cables.

Given the societal, economic, and national security importance of cables-and the threats they face-greater emphasis must be placed on their protection, repair, and redundancy.