Ireland Bolsters Naval Capabilities Amid Rising Subsea Security Concerns

Ireland is undertaking a significant modernization of its Naval Service, shifting its focus from traditional fisheries protection to safeguarding critical underwater infrastructure and deterring potential espionage and sabotage. This transformation comes amid increasing activity by Russian vessels in Irish waters and a growing awareness of vulnerabilities to subsea data cables and energy networks.

From Constabulary Force to Offshore Territorial Defence

For decades, the Irish Naval Service, often described as operating “civilian hulls painted grey,” has primarily focused on fisheries enforcement. Though, the evolving geopolitical landscape and the increasing importance of undersea infrastructure are driving a fundamental change in mission. According to a 2000 White Paper, over 90% of naval operations were related to fisheries protection [1]. Now, officials aim to elevate the service to a level six “offshore territorial defence navy,” a significant step up from its current status as a “token navy” focused on constabulary duties [1].

Addressing Subsea Threats

The impetus for this change stems from several factors, including the presence of Russian vessels like the Yantar, believed to be capable of intelligence gathering and potential sabotage of underwater infrastructure [1], [3]. The Russian “shadow fleet” of aging tankers traversing Ireland’s Exclusive Economic Zone (EEZ) also raises concerns, though the primary worry centers on activity beneath the waves [1]. Western security services have expressed concerns that the Yantar is equipped to map and potentially sabotage critical infrastructure, utilizing a moon pool for deploying mini-submersibles [1].

Technological Upgrades and International Cooperation

The modernization plan involves equipping existing ships with advanced technology, including towed sonar arrays purchased from French defence company Thales for approximately €60 million [1]. These arrays will utilize both active and passive sonar to detect underwater activity. The four Beckett-class offshore patrol vessels will also receive medium-range air-search radar to counter airborne threats, such as the drones spotted during Ukrainian President Volodymyr Zelenskiy’s visit in December 2025 [1], [2], [3], [4]. Electronic warfare systems capable of jamming drones and sensors will also be installed [1].

Ireland is also strengthening cooperation with France and the UK to deter potential threats and will seek assistance in identifying unknown vessels detected in its waters. The Defence Forces will deploy C295 maritime patrol aircraft and sonobuoys to supplement sonar capabilities [1]. The government intends to collaborate with private companies owning subsea infrastructure, encouraging them to host sensors for enhanced protection.

National Maritime Security Centre and Data Sharing

Information gathered from these various sources will be consolidated at a new national maritime security centre and shared with EU nations through the Common Information Sharing Environment system [1]. While the new technology will detect underwater objects, identifying their origin and intent will remain a challenge, necessitating reliance on international partners for positive identification.

The overall goal is deterrence, with the expectation that the increased surveillance capabilities will discourage hostile activity. Officials believe that simply the prospect of detection is often enough to deter potential adversaries [1].