Ireland and Britain conduct first subsea telecoms cable security exercise

Ireland and Britain are examining the results of the first-ever joint exercise simulating disruption to “multiple communication cables” in the Dublin region.

The test was described as a “realistic scenario” affecting sub-sea telecoms cables connecting the two countries. There are an estimated six digital cables landing in the Dublin region that connect to Britain over the Irish Sea.

While disruption to one cable has been described as not being detrimental to telecoms services — given the resilience in the system and the availability of sister cables — an attack on multiple cables at the same time could have a serious impact.

The disruption would affect the organs of State and public services, including public utilities, in addition to financial and business services, and the daily lives of citizens.

The Department of Culture, Communications and Sport said that both it and the UK’s Department for Digital, Culture, Media and Sport jointly conducted an exercise, codenamed ‘Eastern Pearl’.

The purpose was to “validate and enhance Ireland and the UK’s co-ordination and response capabilities to a realistic scenario affecting subsea telecoms cables”. Representatives from across government were involved as observers.

The department said Ireland and the UK had developed a joint framework formalising how both governments would “ information, co-ordinate decisions and respond jointly” to disruption affecting subsea telecoms cables connecting both nations.

It said it formed part of the commitment outlined in the UK-Ireland 2030 programme agreed by the Taoiseach and UK prime minister in March 2025 to strengthen co-operation in the area of critical undersea infrastructure.

Patrick O’Donovan, minister for culture, communications and sport, said: “[This] successful exercise marks a key milestone in the development of enhanced co-operation between Ireland and the United Kingdom in preparing for disruption to our shared critical undersea infrastructure.

“Strengthening partnerships and working relationships with our neighbours will be key to improving the resilience of the network of international subsea telecoms cables serving Ireland, the UK and Europe.”

Protecting Ireland’s critical undersea infrastructure is also one of six objectives of the National Maritime Security Strategy 2026-2030 .

That strategy, published last February, noted “growing concern at the threats posed by Russia’s shadow fleet”, including their possible use in both espionage activity, through use of drones, and sabotage, by deploying anchors along the seabed to cut cables.

It said that “deliberate but deniable damage from anchor drags [was] possible”. It said Ireland was “particularly reliant on submarine cables” for its connectivity to the outside world and because the country was “a hub for major tech companies”.

Cormac O’Keeffe, security correspondent

TODAY

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