Securing our shared seas: A new era for British-Irish naval cooperation?
The Memorandum | No. 07.2026
World leaders have recently concluded the latest Munich Security Conference, Russia continues its full-scale invasion of Ukraine and the policies of the current United States (US) administration are increasingly perceived to threaten international peace and stability. In this context, critical maritime security threats loom larger than ever.
Such threats are increasingly interconnected and sophisticated, with the conflict in Ukraine in particular increasing pressures on global energy supplies. This has resulted in Russia deploying a ‘shadow fleet’ of vessels to evade economic sanctions, and leading directly to attacks on undersea infrastructure in the Baltic Sea.
As two of the most exposed island nations sitting at the western fringes of Europe, and with large maritime territories spilling out into the northeast Atlantic, the United Kingdom (UK) and Republic of Ireland appear particularly vulnerable in the face of such threats – not least because a significant proportion of the world’s undersea cables and pipelines either pass through or close to their waters. Given mutual dependencies, as well as evident capacity constraints on Ireland’s side, deeper bilateral cooperation between both countries to counter existing and emerging maritime security threats is ever more essential.
Such cooperation is well-established, and strongly valued from both sides. It builds on shared geography, history and practical necessity. Nevertheless, at the start of 2026, Britain and Ireland are at a turning point. With an updated Memorandum of Understanding (MOU) on bilateral defence cooperation expected imminently, and with Ireland also currently finalising its first National Maritime Security Strategy (NMSS), there are clear indications of new approaches and investments from both nations in mutual and cooperative efforts to counter maritime threats.
British and Irish maritime developments
Following a report of the Parliamentary Joint Committee on the National Security Strategy from September 2025, His Majesty’s (HM) Government subsequently announced that it intends to establish a new Undersea Infrastructure Security (UIS) Oversight Board, chaired by the Cabinet Office, to set strategic direction across diverse government departments responsible for the operation, security and resilience of undersea infrastructure, among other aspects.
Such commitments came after HM Government had announced details of its ‘Atlantic Bastion’ programme, designed to strengthen protection of undersea cables in the North Atlantic. This programme seeks to combine the use of autonomous vessels, deployed with Artificial Intelligence (AI) technology alongside more traditional warships and patrol aircraft, creating an ‘advanced hybrid force’.
On the Irish side, in anticipation of the publication of the NMSS, there have already been announcements on investments in new technology, including towed sonar arrays to monitor threats to undersea infrastructure. Given obvious capacity constraints, however, much of Ireland’s focus has been increasingly multilateral in orientation – for instance, the Irish Naval Service’s Offshore Patrol Vessel (OPV) LÉ William Butler Yeats participated in a Passing Exercise (PASSEX) with North Atlantic Treaty Organisation (NATO) warships off the Irish coast in an effort to improve interoperability between available assets.
Of course, this kind of defence collaboration is a sensitive subject within Ireland, with many perceiving it as a threat to the nation’s policy of military neutrality.
These efforts have been much more noticeable in intelligence sharing and data gathering. For example, Ireland decided to join NATO’s Individually Tailored Partnership Programme (ITPP) in 2024. For similar reasons, in April 2025, the Irish Defence Forces also joined the European Union’s (EU) Common Information Sharing Environment (CISE). This seeks to improve information sharing across maritime authorities between Ireland and other EU partners in order to detect threats to critical undersea infrastructure.
Of course, this kind of defence collaboration is a sensitive subject within Ireland, with many perceiving it as a threat to the nation’s policy of military neutrality. As Ireland increasingly adopts a ‘collective security’ approach, cooperating in European and NATO-led initiatives, Irish leaders have been careful to point to cooperation with other militarily neutral states, such as Switzerland, to highlight how important multilateral defence collaboration can still go hand-in-hand with an ostensibly neutral geopolitical standpoint.
The future of British-Irish maritime cooperation
It is clear that collaborative efforts between the UK and Ireland will be increasingly essential to ensuring maritime security in the North Atlantic, particularly as both countries cooperate further in infrastructure development and investments in future technology, and increase their energy interconnectedness. This is especially reflected in the outcome of a joint summit from March 2025, where Sir Keir Starmer, Prime Minister, and Taoiseach Micheál Martin sought to strengthen cooperation in maritime security, with a particular focus on the protection of critical undersea infrastructure.
The subsequent joint statement closed with a commitment to the establishment of a UK-Ireland 2030 Steering Group, led by the Cabinet Office and Department of the Taoiseach. The Steering Group also complements existing cross-border institutions established under the auspices of the 1998 Good Friday Agreement. This makes clear that the kind of joint investment and regulatory alignment anticipated – in particular to further the offshore energy sector – will depend upon joint cooperation in data gathering and intelligence sharing to counter the security threats to such infrastructure.
To monitor and protect such infrastructure adequately, progress should be made on engaging properly with other government departments and processes, such as in relation to maritime planning authorities.
These commitments will find expression in the imminently anticipated bilateral defence MOU, which is expected to highlight an increased focus on, inter alia, joint military training and education, as well as within Ireland’s forthcoming NMSS. The NMSS itself will likely place the greatest emphasis on enhanced commitments to multilateral cooperation in this area.
The expectation is that the commitments will soon bear fruit. Indeed, proposals from the British-Irish Parliamentary Assembly have suggested the necessity of establishing a joint statutory Cables Protection Commission, with the aim of monitoring and securing critical subsea infrastructure. It was recommended that this body include representatives from government and defence, as well as owners of undersea assets. Alongside comprehensive mapping of such infrastructure, the Commission would oversee monitoring patrols and efforts to enhance resilience of undersea infrastructure through the intermeshing of communications networks.
Moves like this also signal the importance of a final plank to efforts to shore up maritime security regarding undersea cables and pipelines. To monitor and protect such infrastructure adequately, progress should be made on engaging properly with other government departments and processes, such as in relation to maritime planning authorities. Private sector actors should also get involved due to ownership of undersea assets as well as in terms of efforts to enhance monitoring and surveillance more broadly across the maritime sector.
None of these priorities will be delivered easily. However, it is clear that there has never been as much political impetus and institutional momentum for the UK and Ireland to work together to meet these challenges.
Dr Richard Collins is Professor of International Law and Dean of Internationalisation and Engagement in the Faculty of Arts, Humanities and Social Sciences at Queen’s University Belfast. His research interests coalesce around the law of the sea, global governance and international institutions, with a particular focus on maritime borders and dispute settlement.
This article is published in association with Queen’s University Belfast as part of the International Sea Power Conference 2025.
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