Strategic Defence Review 2025: The British Army

The army will become ten-times more lethal, the Defence Secretary, John Healey, pledged in his foreword to the Strategic Defence Review (SDR), published by the government in June 2025:

We will create a British Army which is 10x more lethal to deter from the land, by combining more people and armoured capability with air defence, communications, AI, software, long-range weapons, and land drone swarms.

The SDR discusses the ways in which warfare is changing, but states that the army’s principal role – to project military force from land - will continue to play a fundamental role in deterring and defeating adversaries. But to do so, particularly to fulfil one of its core tasks, which is to support NATO’s ‘deterrence by denial’ approach in the Euro-Atlantic, the army will require greater lethality, mass and endurance.

Specific roles for the army include contributing to homeland defence and resilience plans, providing one of two strategic reserve corps to NATO, able to deploy rapidly when needed, and training and working alongside key allies and partners.

The review says that the army can deliver a “ten-fold increase in lethality by harnessing precision firepower, surveillance technology, autonomy, digital connectivity, and data”. The review explains this ten-fold increase will be measured against a conventional armoured brigade model.

Alongside the greater use of AI and autonomy, the SDR envisages the creation, by 2027, of a “digital targeting web”, that could connect “sensors, deciders and effectors” to enable “choice and speed” in deciding the response to any identified threat, across all domains.

The review laud’s the army’s ‘recce-strike’ model for land fighting power: the army’s ability to find (recce) and destroy (strike) enemy targets. The review says this new model should “underpin the transformation of the two divisions and Corps Headquarters committed to NATO’s Strategic Reserves Corps”.

The review suggests the army’s Project Asgard will ‘enhance’ the recce-strike model. The army says the Asgard digital system will “improve the accuracy of targeting enemies and reduce decision-making time for strikes”.

The review confirms that long-standing core army equipment - armoured platforms (vehicles) and attack helicopters - will still be needed to confront a major state adversary. But it argues that autonomous and uncrewed systems have become an “essential component of land warfare”. The SDR envisages the army’s future capabilities to be a dynamic ‘high-low’ mix of equipment, in which autonomous and uncrewed platforms are paired with traditional armoured platforms.

The army already has some capability enhancements already underway: Challenger 3 tanks, and Ajax and Boxer armoured vehicles. Colonel Rupert Kitching, Assistant Head Army Strategy London, said the recapitalisation of these platforms “provides the essential foundation upon which the army will integrate transformative technologies”.

The SDR did not set out an explicit future force model nor did it recommend set numbers for major platforms.

The review recommends that the regular army should not drop below 73,000, and there should be a minimum of 100,000 regular and reserve personnel.

The review called on the army to be able to “rapidly expand and mobilise Reserve forces” and should reinvigorate the active and strategic reserves. It prioritises training to restore the army’s readiness to fight at all levels, and notes that while advanced simulation can provide effective and efficient training, live firing over distance remains essential.

Further information on the current size of the armed forces can be found in Commons Library briefing: Strategic Defence Review 2025: Armed forces personnel.

The review highlights the army’s contribution of two divisions and a Corps HQ to NATO’s strategic reserve corps (SRC). These are forces held at readiness, able to deploy anywhere when required by the Supreme Allied Commander Europe (SACEUR). Al Carns, the Minister for the Armed Forces, has described the SRC as SACEUR’s “most credible warfighting land force”. UK troops offered to NATO as part of the SRC are held at a readiness of 31 to 180 days.

To further support NATO readiness, the review suggests the UK should consider prepositioning ammunition and heavier equipment in storage facilities on the European continent.

The review allocates responsibility for the army’s contribution to the planning, preparation, and delivery of defence support to national resilience to Standing Joint Command (UK). This is the army’s supporting command, responsible for recruitment and training.

However, the review notes that in a time of war, the army’s capacity to support national resilience would be limited:

With most of the Army’s deployable capability committed to NATO, its capacity to support domestic resilience would be significantly reduced if it were mobilised for war.

This briefing is part of series of Commons Library briefings on the 2025 Strategic Defence Review. It examines the key elements of the review as they relate directly to the army. Recommendations made by the review are highlighted in boxes. This briefing does not include commentary or reaction to the proposals.