Dominating the subsea domain in a new age of undersea warfare
- Nov 18, 2025
- 3 min read
by Chris Cook
Chris joined BAE Systems Digital Intelligence in March 2023 as Digital Defence Business Development Director, after 31 years in the Royal Navy. Within a wide Defence remit, part of his current role includes a focus on delivering capabilities to securely connect assets in the subsea environment. In uniform, Chris’s key roles included Head of Strategy at Defence Digital, Programme Director for SkyNet 6, and UK Executive Member of the Five Eyes Combined Communications Electronics Board. Chris is a graduate of the Royal College of Defence Studies, and holds degrees from Durham, Portsmouth, Cranfield and Kings College London.
This article explores the strategic importance of the subsea domain in modern defence, highlighting its critical role in global telecommunications, financial systems, and national security. With over 95% of intercontinental data transmitted via subsea cables, recent incidents of sabotage and geopolitical tensions have underscored the vulnerability of undersea infrastructure.
Chris Cook argues that traditional defence capabilities are increasingly inadequate against emerging threats in the subsea environment. He identifies three key areas requiring urgent attention: Intelligence, Surveillance and Reconnaissance (ISR), Anti-Submarine Warfare (ASW), and Critical Undersea Infrastructure Protection (CUI-P). The article calls for investment in autonomous systems, dynamic underwater networking, and next-generation communications technologies to enable real-time intelligence sharing and wide-area surveillance.
The piece concludes by urging UK industry and defence stakeholders to accelerate capability development and integration, aligning with strategic initiatives like the Royal Navy’s Atlantic Bastion and NATO’s Digital Ocean. The subsea domain, once overlooked, is now a pivotal battlespace requiring robust, forward-looking solutions to safeguard prosperity and security.
Why it matters
You may be wondering why an article on winning the competitive edge in the subsea domain is appearing in the predominantly Land-focussed Journal of the Royal Corps of Signals. Some statistics from the recent report “Subsea telecommunications cables: resilience and crisis preparedness” by the Joint Committee on the National Security Strategy prove why this subject should matter to us all:
Around 570 cables (plus a further 80 planned) carry between 95-99% of the world’s intercontinental telecommunications data
Just two cables account for 75% of the UK’s transatlantic capacity
High-frequency trading and other financial services rely on subsea cables, with $1.5 trillion in cross-border trading (23% of the world’s total) travelling through subsea cables every day
The challenge we face is that the subsea domain is becoming increasingly contested, congested and complex with threats growing in frequency and severity. This is all putting these cables, and UK national security more generally, at risk – with various recent incidents demonstrating the growing threat. Last year, two fibre-optic cables running under the Baltic Sea from Germany to Finland and Sweden to Lithuania were severed, followed by Estonia’s power supply being significantly impacted when the main undersea electricity cable linking Finland with Estonia was damaged.
These incidents captured global interest in suspected subsea infrastructure sabotage at a time of heightened geo-political tensions, prompting NATO to increase surveillance of ships in the Baltic Sea with aircraft, warships and drones through a new “Baltic Sentry” mission. The threat was also spotlighted in the UK government’s 2025 Strategic Defence Review, which emphasised maritime security as a “strategic imperative for the UK” and referenced the Royal Navy’s ‘Atlantic Bastion’ plan to “secure the North Atlantic for the UK and NATO against the persistent and growing underwater threat”.