Policy versus reality: The ‘DIP’ in British defence credibility

William Reynolds looks at the UK’s Defence Investment Plan and argues that the resources outlined match neither the commitments of the Strategic Defence Review nor the urgency of the challenges we face.

In February 2026, the UK Prime Minister Sir Keir Starmer warned the Munich Security Conference that past leaders had “looked the other way, only re-arming when disaster is upon them”, and called for a rebuilding of “hard power…the currency of the age.” Fast forward four months, his Defence Secretary, John Healey, tendered his resignation, claiming the Prime Minister was “unable, and the Treasury unwilling, to commit the resources that the nation needs to defend the country”. The Defence Investment Plan (DIP), the Ministry of Defence’s response to the 2025 Strategic Defence Review (SDR) was not resourced to meet the agreed upon recommendations of the latter document. With the NATO conference in Ankara fast approaching, Britain risks having lectured for increased spending without producing the goods.

Drawing upon new research conducted with Prof Jamie Gaskarth and Dr Maeve Ryan, it becomes clear that this gap between rhetoric and reality undermines the UK’s credibility as a committed, ‘leading’ power to the NATO alliance.

The SDR itself suffered from a vague defence process, which led to a lack of clarity and prioritisation. The Review provided three general ‘Roles’ which defence was required to do– Role 1: defence of the UK and overseas territories; Role 2: successfully deterring and/or winning any fight which would occur in the Euro-Atlantic area; and Role 3: being able to shape the global security environment. Under the umbrella of ‘NATO First’, ensuring the UK “plans”, “thinks” and “acts” with NATO being the core priority in mind, these Roles are laid out for each military domain’s capabilities (Land, Sea, Air, Space and Cyberspace/Electromagnetic Spectrum) and focusses on the idea of ‘warfighting’ (fighting a peer enemy) and being able to deter a war from occurring in the first place. Examples are also provided for each, such as the Navy’s plan for ATLANTIC BASTION, a hybrid-fleet of crewed and uncrewed vessels protecting the Greenland-Iceland-UK maritime gap from Russian submarines; the British Army’s move towards a ‘Recce-Strike’ model for its land forces; and the Royal Air Force’s balance between crewed and uncrewed aircraft in its future.

The problem lies in a lack of clarity about what achieving these ‘Roles’ would mean in practice as a whole package. Role 2, defence of the Euro-Atlantic area, could range from a maritime-focussed defence of the ‘High North’ area to a doubling down on the British land-centric focus around the Baltic area. Both examples would fall under a ‘NATO first’ umbrella, but their geographical and political differences require significantly different capabilities and signal different priorities to different European states. The examples that were given are examples only, with no sufficient explanation as to how they fit into the wider armed forces’ force structure and priorities. Even with the late publication of the DIP, European allies remain unsure of British focus and current commitments, which stretch from Estonia to Iceland. Outside of some notable examples, no explanation of force structure, or specific numbers on formations and equipment have been provided. Contrast this with the Cold War, where the Defence Review of 1975 clearly defined British commitments around the ‘Four Pillars’ of defence, with a clear framework, outline of what the armed forces would look like going forward, and equipment numbers, from which allies could measure British efforts and focus.

This lack of clarity is compounded by the gap between government commitments and the resources allocated to achieve them. The 2025 SDR promised 2.6% of Gross Domestic Product (GDP) on defence by 2027, with an “ambition” to reach 3% in the next Parliament. No expert looking at the recommendations and the resource envelope concluded this was possible. Providing a fully-kitted Carrier Strike Group, funding for the Global Combat Air Program with Italy and Japan, the AUKUS nuclear attack submarine replacement programme and two Divisions with a Headquarters to NATO’s Strategic Reserve Corps, alongside many other recommendations, was never going to be achievable at 2.6%.

To meet these requirements, the Ministry of Defence calculated that an additional £28 billion over four years, on top of the 2.6%, would be needed, with £18bn being the absolute floor for defence without requiring a reduction in the size and capability of the armed forces. For this reason, both John Healey and Al Cairns resigned, as the offered £10-13.5bn was far below even this threadbare requirement. The final increase was £15bn, still £3bn below the minimum threshold. How then the UK is expected to reach the agreed NATO target of 3.5% of GDP by 2035, which is predicted to require an extra £30bn a year, seems unclear. Indeed, the British Chief of Defence Staff noted recently that even more (3.5%) was necessary to “deliver the vision” set out in the SDR and agreed upon by the Prime Minister.

In 2021, the SDR’s predecessor, the Integrated Review, called for the UK to use its “convening power” to bring together partners to meet shared challenges. Britain has long played on its role as the leader of defence within Europe, but this is no longer the case. Germany, Poland, Norway and many others have significantly pushed their defence spending above and beyond 3% of GDP.

There is growing “frustration” with the UK’s rhetoric on defence. Despite regularly referring to itself as a leading European nation of NATO, the atrophy of the armed forces no longer reflects this. European defence firms and allies have noted the slowness of Britain’s translation of promises to reality. Whilst both NATO and the European Union have called for its members to be ready to deter or fight Russia by 2030, reportedly the UK currently sits at 31 of 32 on a NATO league table of rearmament. The spending gap will only deepen the issue.

Yet , despite the significant overstretch, successive governments has continued to reach for the armed forces as a preferred response to crises, setting commitments like de-mining in the Middle East, a possible Coalition of the Willing in Ukraine, alongside the vagueness of the SDR, without the commensurate resources to facilitate it. Indeed, the Prime Minister “disagrees” that said resources are required. The consequences are a stretched to breaking-point armed forces, unfulfilled promises and resulting loss of confidence from European partners in British defence capability. It is time political rhetoric matched reality. Either the UK accepts a reduced defence role in Europe, or it puts its money where its mouth is.

By Dr William Reynolds, Advanced Education Pathway (AEP) Lecturer in Defence Studies, Defence Studies Department, King’s College London.