UK Must Actively Prepare for Potential Homeland War, Strategic Defence Review Warns

The United Kingdom is gearing up for a new era of defence as its 2025 Strategic Defence Review (SDR) warns of the potential for war on British soil for the first time in decades. The comprehensive review, unveiled by Prime Minister Sir Keir Starmer, outlines an ambitious plan to transform the UK’s military capabilities, bolster homeland defence, and prepare society for the realities of modern conflict. This landmark shift responds to growing threats from Russia, China, Iran, and other hostile actors, emphasizing a “NATO First” policy and a move to war-fighting readiness.

Strategic Defence Review 2025: A New Defence Paradigm

Moving to War-Fighting Readiness

The SDR sets out a decisive pivot from a posture of deterrence to one of active war-fighting readiness. It acknowledges that the UK’s armed forces currently face challenges such as depleted weapon stockpiles, recruitment shortfalls, and morale issues, leaving them ill-equipped to confront peer adversaries like Russia or China. The review calls for reversing this trend by investing heavily in modernising and expanding the military to meet the demands of potential state-on-state conflict.

NATO First and European Security Leadership

Central to the UK’s new defence strategy is a “NATO First” approach, reinforcing the country’s commitment to the alliance as the cornerstone of its security. The UK pledges to lead European security efforts and strengthen NATO’s collective defence, ensuring it will never fight alone. However, the strategy also maintains global partnerships beyond NATO, reflecting the interconnected nature of modern security threats.

Major Investments and Capability Enhancements

Defence Spending and Industrial Growth

The government commits to increasing defence expenditure to 2.6% of GDP by 2027, with ambitions to reach 3% in the subsequent parliamentary term. This marks the largest sustained increase in UK defence spending since the Cold War.

Key investments include:

• Nuclear deterrent: A £15 billion investment in the sovereign Astraea nuclear warhead programme, alongside the construction of up to 12 SSN-AUKUS nuclear-powered submarines, ensuring a credible and modernised nuclear deterrent.
• Munitions and missiles: Establishing six new munitions factories operating at full capacity with an “always on” production pipeline and procuring up to 7,000 domestically produced long-range and cruise missiles to replenish depleted stockpiles.
• New Hybrid Navy: Developing a versatile naval force combining aircraft carriers, warships, submarines, autonomous vessels, and drones to patrol the North Atlantic and beyond.
• Army modernisation: Creating an army that is “10 times more lethal” by integrating air defence, AI, software, long-range weapons, and land drone swarms to enhance battlefield effectiveness.
• Royal Air Force upgrades: Introducing next-generation fighters including F-35s, upgraded Typhoons, and autonomous aircraft to maintain air superiority and global strike capability.
• Cyber and homeland defence: Establishing a new CyberEM Command to defend against daily cyberattacks and investing up to £1 billion in homeland air and missile defence systems to protect critical infrastructure.

Defence Innovation and Industrial Partnerships

The SDR emphasises innovation driven by lessons from the Ukraine conflict, harnessing drones, AI, and digital warfare to maintain technological superiority. A £400 million Defence Innovation Fund will support UK businesses, while a new Defence Exports Office aims to boost international sales of British defence products.

Preparing Society for Conflict: A Whole-of-Society Approach

Resilience and Public Preparedness

For the first time in decades, the UK government is openly preparing its civilian population for the possibility of war on home soil. The SDR calls for a “whole-of-society” resilience strategy, encouraging public participation in national security and readiness to support the military during crises. This approach draws inspiration from Nordic countries’ civic models, aiming to strengthen social cohesion and economic resilience in the face of sabotage, cyberattacks, and information warfare.

Potential Threats to the Homeland

The review details the likely effects of conflict on the UK, including:

• Air and missile attacks using drones, cruise, and ballistic missiles targeting military bases and critical infrastructure.
• Frequent sabotage and cyberattacks against energy grids, communication networks, and undersea fiber optic cables.
• Disruption of global supply chains critical for minerals, gas, and food imports.
• Information manipulation campaigns designed to undermine political will and social unity.

Prime Minister Starmer highlighted the daily reality of these threats, noting the UK faces “very, very frequent and very, very serious” cyberattacks and energy security challenges. He pledged to transform the UK into a “battle-ready, armour-clad nation” prepared for a dangerous decade ahead.

Political and Military Reactions

Government Endorsement and Implementation

The government has accepted all 62 recommendations of the SDR and is moving swiftly to implement them, including introducing a Defence Readiness Bill to enable rapid mobilisation of reserves and industry in times of crisis.

Defence Secretary John Healy underscored the necessity of making the armed forces significantly more lethal and technologically advanced to deter and, if necessary, prevail in future conflicts.

Opposition and Criticism

Some opposition voices have criticized the review’s proposals as underfunded and lacking ambition. Conservative shadow defence secretary James Cartlidge described the SDR as a “damp squib,” questioning whether the investments would be sufficient to meet emerging threats.

Challenges Ahead

Despite the ambitious plans, the UK faces significant hurdles:

• The British Army is currently at a historic low strength of approximately 72,510 troops, below previous targets, raising concerns about manpower and readiness.
• The complex global supply chains the UK depends on remain vulnerable to disruption in conflict scenarios.
• The rapidly evolving nature of warfare demands continuous adaptation and innovation to stay ahead of adversaries.

The UK’s 2025 Strategic Defence Review marks a historic turning point, signaling a robust shift toward preparing for potential war on its own soil. With substantial investments in nuclear deterrence, conventional forces, cyber defence, and societal resilience, the UK aims to become a more lethal, technologically advanced, and resilient nation. As geopolitical tensions rise, this comprehensive strategy reflects a sober recognition of emerging threats and a commitment to safeguarding the homeland and its interests at home and abroad.