Updated UK-Ireland Memorandum of Understanding on Defence Cooperation (2026)

The UK and Ireland have signed a refreshed Memorandum of Understanding (MoU) to modernise and deepen their bilateral defence cooperation. The agreement was signed on 13 March 2026 by UK Defence Secretary John Healey and Irish Minister for Defence Helen McEntee, coinciding with the UK–Ireland Leaders' Summit held in Cork, where Prime Minister Keir Starmer met Taoiseach Micheál Martin.

The updated MoU replaces the previous agreement signed in 2015 by then Defence Secretary Michael Fallon and Irish Minister Simon Coveney. It fulfils a commitment made by both governments at the 2025 UK–Ireland Leaders Summit to update the agreement in line with the strengthened and evolving partnership between the two countries.

🌊 What Are the Key Areas of Enhanced Cooperation?

The refreshed MoU sets out four areas where cooperation between the UK Armed Forces and the Irish Defence Forces will be strengthened.

Maritime Security

Both countries will strengthen their joint efforts to protect critical undersea infrastructure, such as cables and pipelines that sit on the seabed. This is increasingly important as such infrastructure has come under threat from deliberate sabotage across Europe. The MoU also provides for improved response mechanisms to maritime security incidents, and expanded cooperation between UK and Irish forces in the maritime domain.

Cyber Defence

The UK and Ireland will increase information sharing to improve joint situational awareness, meaning both governments will have a clearer picture of the threats they face online. The agreement also includes measures to strengthen resilience against cyber threats.

Air Domain Information Sharing

Both governments will enhance the exchange of airspace related information and improve coordination to address shared air security challenges. This means the two countries will have a better, more joined up picture of what is happening in the airspace they share.

Joint Procurement

The MoU opens the door to exploring joint procurement opportunities for military equipment, as well as the potential for new Government to Government sales. Buying equipment together can reduce costs and improve interoperability between the two countries' forces.

🤝 What Broader Cooperation Does the Agreement Cover?

Beyond the four new focus areas, the MoU reinforces ongoing cooperation that already exists between the UK and Ireland across a range of defence and security activities:

💬 What Have Ministers Said?

💷 A Period of Increased Defence Investment

The signing of this MoU comes at a time when the UK has been significantly increasing its investment in defence and military innovation. In December 2025, the government announced a rapid £140 million investment in drone and counter drone technology through the newly formed UK Defence Innovation (UKDI), the first major tranche of a wider £400 million annual innovation budget. That investment included funding for AI submarines, laser weapons, and autonomous helicopter development.

The Ministry of Defence has also held several competitions to drive innovation, including a £1 million competition through the Defence and Security Accelerator (DASA) to develop autonomous sensor technologies capable of detecting, classifying, and tracking objects with minimal human input.

The refreshed MoU with Ireland sits within this broader context of the UK modernising its defence capabilities and deepening cooperation with partners in response to evolving security threats.

🧩 Why Does This Matter?

The UK and Ireland are close neighbours with a long history of working together on defence and security. The original 2015 MoU established the formal framework for that cooperation, but the security landscape has changed significantly in the decade since. Threats to undersea infrastructure have grown, cyber attacks have become more frequent and sophisticated, and the war in Ukraine has reshaped European security thinking.

By refreshing the MoU, both governments are signalling that they want their cooperation to keep pace with those evolving threats. The agreement also puts existing informal arrangements on a more formal and transparent footing, which the Irish Minister for Defence highlighted as a priority.

For Ireland, the MoU is notable given the country's policy of military neutrality. The agreement is careful to respect the distinct defence and security policies of both nations, meaning it does not require Ireland to join any alliance or take on commitments that would compromise its traditional stance.