The UK government has unveiled its landmark 2025 Strategic Defence Review (SDR), marking the largest sustained increase in defence spending since the Cold War and a decisive shift toward “warfighting readiness.” While the review outlines ambitious plans to expand the Army, modernize the Royal Navy with new nuclear-powered submarines, and invest heavily in advanced technologies, it notably leaves the country’s military space strategy vague and unresolved. This article explores the key elements of the SDR, its implications for UK defence posture, and the mixed reactions it has sparked.
A New Era of Defence: Key Highlights from the 2025 Strategic Defence Review
Major Investment and Expansion Plans
The UK government commits to raising defence spending to 2.5% of GDP by 2027, with an ambition to reach 3% in the following parliamentary term — a significant boost reflecting the rising geopolitical threats. Central to the review is the acquisition of up to 12 new nuclear-powered attack submarines (SSNs) through the trilateral AUKUS partnership with the US and Australia, intended to replace the current Astute-class fleet and ensure undersea dominance from the late 2030s.
In parallel, a £15 billion investment will sustain the UK’s sovereign nuclear warhead program, underpinning the Continuous At Sea Deterrent (CASD) for decades to come and supporting approximately 9,000 jobs directly, with thousands more in supply chains7.
The British Army is set to expand to at least 76,000 full-time personnel, with a 20% increase in the Army Reserve, aiming for a total force of around 112,000 including reserves. The Army Cadet Force will grow by 30% to 250,000 cadets by 2030, introducing new “gap year” opportunities to attract youth into military careers.
Technological Modernization and Warfighting Readiness
The SDR emphasizes transforming the UK armed forces into a “10 times more lethal” force by integrating cutting-edge technologies such as artificial intelligence, autonomous drones, long-range precision weapons, and directed energy systems like the DragonFire laser. The Royal Navy will develop hybrid carrier air wings combining crewed F-35B jets with autonomous platforms and expendable drones armed with long-range missiles, enhancing maritime strike capabilities.
Additionally, the review commits £1.5 billion to improve forces’ housing and living conditions, alongside £7 billion for broader defence infrastructure upgrades. It also prioritizes munitions production, pledging £1.5 billion to build six new factories and procure 7,000 long-range weapons, ensuring a steady supply for sustained conflict scenarios.
Cyber and Intelligence Enhancements
Recognizing the growing cyber threat, the review allocates £1 billion to establish a “Digital Targeting Web” to accelerate battlefield decision-making and integrate weapon systems more effectively. A new Cyber and Electromagnetic Command will oversee defensive and offensive cyber operations, including electronic warfare capabilities to disrupt enemy drones and missile systems.
Military Space Strategy: Still Up in the Air
Despite the comprehensive nature of the SDR, the UK’s military space strategy remains notably underdeveloped. The review acknowledges the critical role of space-based capabilities, particularly for persistent overhead Intelligence, Surveillance, and Reconnaissance (ISR) to support integrated air and missile defence in the Euro-Atlantic region7. However, it stops short of defining a clear strategy or naming partners, leaving the UK’s approach to military space uncertain and unresolved.
This ambiguity contrasts sharply with the detailed commitments in other domains and has raised questions about the UK’s readiness to compete in the increasingly contested space environment, where adversaries are rapidly advancing their capabilities.
Political and Expert Reactions
Government Perspective
Prime Minister Sir Keir Starmer framed the SDR as a “root and branch” overhaul, asserting the UK must be ready to “fight and win” a full-scale war amid a “more dangerous and volatile” world. Defence Secretary John Healey emphasized the shift to warfighting readiness as the armed forces’ central purpose, highlighting the importance of nuclear deterrence, advanced technology, and increased personnel.
Healey also underscored the need for hybrid carrier air wings and long-range missile capabilities, despite some analysts questioning the operational practicality of these plans given current carrier limitations.
Opposition and Expert Criticism
The Conservative Shadow Defence Secretary James Cartlidge criticized the review as “underfunded and entirely unimpressive,” labeling the proposed fleet expansions “a fantasy” and warning that the SDR sends a “profoundly weak” signal to adversaries like Russia.
Meanwhile, defence analysts such as Malcolm Chalmers, deputy director general of the Royal United Services Institute (RUSI), described the SDR as potentially the most radical defence review in a generation, driven by the lessons of the Ukraine war and shifting global threats. However, even experts note the lack of clarity on the UK’s military space ambitions as a critical gap.
Strategic Implications and Outlook
The 2025 Strategic Defence Review signals a decisive pivot back to a Cold War-style defence posture focused on homeland defence, deterrence, and readiness to confront peer adversaries such as Russia and China. The commitment to nuclear modernization and a larger, more lethal army reflects a recognition of the changing nature of warfare and the need for credible deterrence.
However, the unresolved military space strategy leaves the UK vulnerable in an era where space assets underpin critical communications, navigation, and intelligence functions. The absence of a clear plan or partnerships in this domain suggests the UK may lag behind other major powers investing heavily in space warfare capabilities.
The review’s emphasis on hybrid forces, digital integration, and autonomous systems aligns with modern warfare trends but will require sustained funding and political will to realize fully. The government’s pledge to increase defence spending offers a positive outlook, though some critics remain skeptical about whether the ambitions can be matched with resources.
The UK’s 2025 Strategic Defence Review marks a historic investment and strategic shift aimed at restoring the country’s warfighting capabilities and deterrence posture. While it lays out bold plans for nuclear submarines, army expansion, and technological modernization, the military space strategy remains conspicuously undecided, highlighting an area requiring urgent attention as space becomes an increasingly contested domain.
As the UK moves to implement the 62 recommendations of the SDR, the coming years will test the government’s ability to translate ambition into capability, ensuring Britain remains safer, secure at home, and strong abroad in a complex global security environment.
