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Ireland and UK Introduce New Subsea Cable Security Protocol

29th October 2026
Global Sentinel specialist subsea telecommunications cable-laying ship
Cable Connections – Global Sentinel is a specialist subsea telecommunications cable-laying ship, pictured here as a general illustration of the vessels used to install and maintain the underwater networks that Ireland and Britain are seeking to protect. The vessel is not connected with the new security agreement or joint exercise. Photo: Wikimedia Commons. Credit: Wikicommons

Ireland and Britain have introduced a new incident-reporting protocol for subsea cables and conducted a joint security exercise, marking a further step in efforts to protect critical maritime infrastructure around the two countries.

The developments were outlined by Minister for Defence Helen McEntee at the EU Maritime Security Conference in Dublin on Wednesday, 28 October.

The new arrangement provides a mechanism for reporting incidents affecting subsea cables, while a joint tabletop exercise, known as Eastern Pearl, tested how the two countries would respond to a potential disruption.

Ireland–UK Maritime Security Cooperation

The measures build on earlier Ireland–UK commitments to joint exercises and closer cooperation on protecting undersea cables.

Subsea communications cables carry vital international data traffic, while undersea energy infrastructure is also central to Ireland's security. McEntee told delegates that 75% of transatlantic cables traverse Irish waters and that more than 80% of Ireland's natural gas arrives through two subsea pipelines.

The Eastern Pearl tabletop exercise examined coordination in the event of cable disruption. The precise date and findings of the exercise have not been disclosed, and no live at-sea exercise was announced as part of this update.

European Maritime Surveillance Plans

A Defence Forces connection to the EU's Common Information Sharing Environment (CISE) is expected to become operational in 2027. The information-sharing arrangement will complement Ireland's participation in the European Defence Agency's Maritime Surveillance project, MARSUR.

The Minister said these tools would improve the State's ability to gather intelligence and exchange information with European partners in responding to maritime threats.

Naval Service Equipment

McEntee also reiterated plans for counter-unmanned aircraft systems aboard Irish Naval Service vessels, alongside military radar and sonar programmes and work to revitalise the naval base in Cork Harbour.

No new Naval Service equipment contract, delivery date or project-specific funding allocation was announced at the conference. The Minister's reference to an approximately 45% increase in overall defence spending since 2022 was not a dedicated Naval Service budget allocation.

The developments follow the publication of Ireland's first National Maritime Security Strategy in February, which identified the protection of critical maritime infrastructure and improved international cooperation as priorities.

The new reporting protocol and the completed tabletop exercise provide tangible progress in that cooperation, although the operational details of the protocol have not been publicly released.

Further details were reported by RTÉ following the Minister's conference address.

Published in Undersea Cables, Navy
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Undersea Cables

Undersea cables are vital to Ireland's connectivity, facilitating high-speed internet, telecommunications, and energy transmission. These cables traverse the Irish Sea, connecting Ireland to the United Kingdom and continental Europe, and play a crucial role in global communications.

Submarine Communications Cables:
Ireland is strategically positioned along major transatlantic communication routes. Approximately 75% of transatlantic cables pass near Irish waters, underscoring the nation's significance in global data transmission.
These cables are typically as wide as a garden hose, with the filaments that carry light signals being extremely thin—roughly the diameter of a human hair. They are sheathed in layers of insulation and protection, with cables laid nearer to shore using extra layers of armoring for enhanced protection.

Energy Interconnectors:
In addition to communication cables, undersea interconnectors are being developed to enhance energy security and support the transition to renewable energy sources. The UK has approved the construction of five new subsea interconnector cables to boost the grid's flexibility amidst rising renewable energy. These projects will link the UK with wind farms in Belgium and the Netherlands, and connect England with Germany, Wales with Ireland, and Scotland with Northern Ireland. The cables, with a combined 6GW capacity, are expected to be operational by 2032, increasing the UK's total interconnector capacity to 18GW.

Security Concerns:
The strategic importance of these undersea cables has raised security concerns. Incidents in the Baltics have heightened awareness about the potential risks to subsea infrastructure. Ireland's historical neutrality and limited defense resources have led to calls for enhanced maritime security and defense investments, including modern surveillance technology and international cooperation. The government's response includes participation in EU security projects and collaboration with neighboring countries on maritime security.

In November 2024, a Russian spy ship, the Yantar, was escorted out of the Irish Sea by the Irish navy after it was found patrolling an area with critical submarine pipelines and cables. The vessel's presence heightened concerns due to its proximity to interconnector cables vital for internet services linking Ireland to the UK, operated by major tech companies such as Google and Microsoft.

Regulatory and Policy Framework:
The protection and maintenance of undersea cables fall under the jurisdiction of national governments, with private companies often responsible for their security. In Ireland, the Department of Communications, Climate Action and Environment oversees the regulation of telecommunications infrastructure, including undersea cables. The Irish Naval Service plays a role in monitoring and protecting maritime infrastructure, including undersea cables. Internationally, the United Nations Convention on the Law of the Sea (UNCLOS) provides a framework for the laying and maintenance of submarine cables, recognizing the "freedom of the seas" and the rights of coastal states.

Conclusion:
Undersea cables are indispensable to Ireland's connectivity and economic infrastructure. Given their strategic importance, ongoing efforts are necessary to ensure their protection and resilience against potential threats. This includes enhancing security measures, international cooperation, and adherence to regulatory frameworks to safeguard these critical assets.