Dangerous Tides 3: Subsea Geopolitics
Jeanne-May Desurmont | 24 January 2025
Summary
Between November 2024 and January 2025, multiple subsea cables were damaged in the Baltic Sea and in Taiwan’s exclusive economic zone, with high suspicion of sabotage involving Chinese and Russian vessels. Investigations are complicated because of irregular practices such as ship identity and AIS tampering as well as geopolitical tensions.
NATO navies have heightened monitoring of subsea cables, deploying joint deterrence operations and tracking suspicious vessels near critical infrastructure.
Growing threats to subsea cables may lead to the deployment of unmanned vehicles for monitoring and investigation, marking a shift toward advanced technologies to counter grey-zone activities and improve attribution.
On 17 and 18 November 2024, two subsea cables. Cinia’s C-Lion 1, linking Rostock to Helsinki and Telia’s BCS linking the Gotland to Lithuania, were damaged in 48 hours in the Baltic Sea. Then, on 25 December, Estlink 2 between Finland and Estonia was also severed. Most recently, on 3 January, the Taiwanese authorities reported the disruption of an international consortium-operated cable from the Trans-Pacific Express Cable System connecting Taiwan with the US, off the coast of Keelung.
While the disruptions were mitigated by rerouting the data traffic to other communication lanes, the main common thread between these incidents is the suspicion of sabotage because they occurred in highly contested waters. The impacts of disrupted cables range from slowed communications to be completely cut from the Internet or the electric grid. For example, in February 2023, two subsea cables were cut between Taiwan and the Matsu island in a two-week span, consequently, it took between 15 to 20 minutes for Matsu’s residents to send a text message and 50 days for the repairs to be completed. This raised the alarm among the civil society about the vulnerability of the 14 submarine cables connecting Taiwan to the rest of the Internet, and potential resilience mechanisms if China was to cut all the cables simultaneously.
Finland, Germany and Sweden have launched investigations to determine the implication of suspicious vessels navigating near the cables during the disruptions. Additionally, Taiwan has asked for assistance from South Korea to investigate the recent incident. In the case of the C-Lion 1 and the BCS, the main suspect is the Yi-Peng 3, a Chinese cargo ship stationnd in the Russian port Oust-Louga. The YiPeng 3 was travelling in the area of the cables and turned off its automatic identification system (AIS) during the night. Then, a Russian tanker Eagle-S, widely believed to be a part of the Russian ghost fleet, is suspected of having disrupted the Estlink 2 cable. Another Chinese vessel, the Shunxin-39, is the main suspect in the South Korean and Taiwanese investigation, especially as the vessel tempered its identity and switched its IMO identification number and transmitters numerous times to confuse the authorities. Vessels who usually use two different sets AIS system are usually trying to conceal illegal, unreported and unregulated (IUU) fishing and there is a high likelihood that they are also engaging in other unlawful activities.
These incidents contributed to the increased tensions around subsea infrastructures since the disruptions of Nord Streams 1 and 2 in 2022. Targeted countries are also labelling these incidents as intentional acts and grey-zone activities. The latter regards all the coercive actions that are occurring just under the threshold of war and the threshold of attribution and which are mixing civil and military components. Sabotage of subsea cables falls into that category as it is very difficult to prove and to attribute, indeed, it would require tracing the ships metre by metre, second by second. Investigations can also be hindered by external interference, for example, China has asked the YI-Peng 3 not to enter the Swedish waters, slowing down the investigation.
The recent incidents in the Baltic Sea have also prompted NATO members to tighten their surveillance around the cables, especially those directly connected to a landing station. For example, the Yantar, a Russian research vessel but suspected to be speciallised in intelligence, was spotted navigating above subsea cables in the Irish Sea and near the French coasts last November. The vessel was escorted by the British, the French and the Spanish navies. Similarly, vessels seemed to follow cable routes in the Atlantic and the Mediterranean and different European navies are relaying to follow them. European navies are deploying joint deterrence operations by sending warships to move suspicious vessels when they are close to the cables.
U.S. Coast Guard photo by Ensign Joshua Romano/Wikimedia
Forecast
Short-term
While instances of sabotage of subsea cables are still rare compared to the number of accidents, the increased rates of sabotage allegations over the past few months are setting a trend. Especially as disrupting subsea cables falls into grey-zone activities, it is highly likely that more cables will be intentionally disrupted following the geopolitical dynamics.
Medium-term
European and NATO countries are starting to be more prepared to react, and investigations are launched almost immediately after a disruption. It is likely that NATO will launch joint operations to surveil and monitor critical infrastructures at sea shortly as well as new intelligence sharing agreements.
Long-term
Given the high attention to subsea cables, it is highly likely that unmanned underwater vehicles and unmanned surface vehicles will be launched to monitor and surveil the subsea cables. The deployment of such technologies might also help investigations and facilitate the attribution of the incidents which will undermine the essence of grey-zone activities.