Subsea Cable Risk a Mix of Bathymetry and Geopolitics

A new study undertaken by a group of researchers from the UAE, Canada, Japan, and Taiwan collates a range of statistics and expert opinion to address an urgent puzzle: Where and under what conditions do states prioritize cable security?

The researchers focused on three contrasting cable systems: Unity/EAC Pacific (Japan–U.S.), Asia-America Gateway (Guam–Hawaii), and Tata TGNTata Indicom (India–Singapore).

The risk to such cables varies predictably with geopolitical tension, peaking during ambiguous periods between peace and overt conflict. During these times, adversaries exploit unclear attribution and uncertain response thresholds to employ “gray zone” actions such as sabotage that disrupt but don’t trigger direct retaliation.

Cable landing sites present likely targets for sabotage due to their accessibility on land. However, some experts believed that they only become more vulnerable during wartime when states no longer seek plausible deniability.

The survey’s findings include that territorial seas and EEZs are more vulnerable than high seas, because sabotage is easier in shallow waters and on wide continental shelves. However, some experts emphasized proximity to the saboteur and level of tension rather than bathymetric considerations.

One interviewee said: “As geopolitical tensions rise, your appetite for risk also goes up.”

The aim of the saboteur is also important. In a time of medium tension between states, the aim would be to create uncertainty and frustration in a target state. In wartime, sabotage would be more targeted towards disrupting communications.

“The results reveal patterned heterogeneity rather than uniform vulnerability: landing stations matter, but not equally; some cable systems are systematically riskier than others; legal maritime zones do not reliably predict exposure; and gray-zone phases between peace and war emerge as especially dangerous windows for selective sabotage,” says lead researcher Brendon J. Cannon.

The researchers propose a six-point policy framework: adopt tiered, scenario-based security postures; prioritize protection at the segment/system level; strengthen early warning for gray zone risks; conduct operationally focused vulnerability assessments; develop regional seas frameworks to pool assets; and ensure national readiness through audits, single points of contact, and codified public–private protocols.