The Curious Case of the Delayed Investment Plan

When ‘At Pace’ Means ‘Snail’s Pace’

If UK media reporting is to be believed, the long-delayed UK Defence Investment Plan (DIP) may finally be imminent or, at least, has received a hard deadline for publication – namely the NATO Summit in July. The DIP was originally intended to be released soon after the Strategic Defence Review in 2025, then was scheduled for ‘the autumn’, before being nearly ready before Christmas. Since then, the government has been reluctant to give any strong indications, beyond providing reassurance it was working ‘flat out’ on the DIP, or ‘at pace’. Those who found this latter refrain – lacking an adjective – grammatically lazy, might have been inclined to suggest it was at a snail’s pace, and it stretched credibility to suggest this was the MOD’s top priority if it still hadn’t appeared a year after the SDR.

The DIP Makes the SDR Reality

The SDR was extremely light on the detail around the size and scale of the transformation of the Armed Forces, with no description of the total cost and timeframe for implementation of the recommendations, and very few individual estimates. This gave the government some room to manoeuvre in terms of meeting the targets and claiming it could be achieved within the new financial parameters of spending 2.5% on defence in 2027 (and 3% ‘in the next Parliament’). While the SDR team claimed cost estimates were done for the review, little was shown in the final document, and when the new settlement for the MOD was announced in the budget, it was clear increases were modest in the early years and mostly took place after 2027. The significance in the DIP is therefore that it is vital to actually determining both the pace and prioritisation for change in the Armed Forces. Without it, the SDR is a list of ambitions and a rational for change, but expressed as a shopping list, and not a sequenced plan.

The lack of this plan is a cause for concern, because the government has taken to arguing it is better to ‘get it right’ than ‘do it quickly’, which is fair enough, but in this case, getting it right seems to be a euphemism for working out what transformation actually costs and then whether it is affordable. Taking a year to do this while the same government is issuing ever-more strident warnings about the state of the world suggests either those warnings are overblown, or getting the sums to add up is proving harder than expected. Neither are reassuring. Stories have emerged that up to £28bn might be needed over a four year period in addition to the current budget for the plan to be ‘affordable’. This only adds to the perception that the delay is over wrangling on the extent to which existing capabilities will have to be cut to afford the change, and that the original, somewhat leisurely route to 2.5% is simply too slow, with no way to reconcile a faster pace and the available resources.

Who Should Read the Investment Plan?

There is therefore a lot riding on the DIP, with multiple audiences for it. Chief amongst these are the personnel and planners for the Armed Forces themselves. While multiple contracts, projects and experiments have been able to proceed during and subsequent to the SDR, this is no substitute for a detailed plan over 10 years, setting out objectives, priorities and targets, which explain where the big investments in defence will actually be made. Without it, the Army can’t know if Project ASGARD will actually be applied across the whole Army; the Navy won’t know what major surface vessels it will have and when, around which to form the Hybrid Navy; the RAF has no idea about the size of the future combat air force and the in-service date for the Global Combat Air Programme; the Digital Targeting Web will survive on scraps; Integrated Air and Missile Defence will be limited and mostly exist as a concept; drone experiments remain side projects; and new missile and munition production remains an aspiration.

The DIP must therefore not only replace the old Equipment Plan but must also expand on it. The Equipment Plans had been becoming progressively less detailed and harder to read over several years, culminating in the Department being unable to produce any detailed figures for scrutiny, much to the anger of the Defence and Public Accounts Committees. The last plan available for scrutiny by the National Audit Office was for 2023 to 2033, but that was a partial plan looking at affordability. The last full plan scrutinised by the NAO covered 2022 to 2032 and was based on older data. In other words, it has been nearly four years since Defence was able to set out what even then was an unsatisfactory level of detail on just one part of its spending.

As the Public Accounts Committee recently argued, the DIP faces the challenge of addressing a deficit of detail and trust amongst several other audiences: political (including those who exercise oversight); the public and media; international partners (especially within NATO); and defence industry. These last two are noteworthy because of the context and rhetoric of the government. The obvious pressure from the current US Administration on defence spending has led to NATO (and by extension the UK Government) agreeing a target of 3.5% of GDP being spent on defence. But ahead of the 2035 target, the government must make a case that the current more modest GDP targets will produce a transformed UK military and therefore make the best of the outputs that can be achieved. The UK is still the third largest defence spender in cash terms, even as its GDP figure (a mark of political prioritisation, more than anything else) places it in the middle of the NATO pack. Meanwhile, while the government announces contracts that have been placed over the past year, the noise from industry – especially smaller companies – has grown ever louder on the damage and economic impact being felt by the lack of certainty. The government cannot both argue the investment plan is vital and there is no consequence to its protracted gestation, especially given the (supposedly) ever-darkening global context.

Evaluating the DIP – and Identifying the Traps

The Defence Investment Plan should be judged by how well it can explain and justify defence spending, plus avoid a few traps that will be indicators of financial or political sleight of hand.

• Details on a spending profile. The investment plan needs to provide a higher level of transparency than the MOD has been able to provide in recent years. That means breaking down the spending by cash types, organisational budgets areas, programmes and projects, on an annual basis in the case of the largest programmes.
• Readiness and support. Before a single extra pound is spent on new equipment, there is an argument that the priorities should include ensuring existing forces and capabilities can be deployed and sustained. That means infrastructure, logistics support (spares), basing and munitions stockpiles all receiving investment that means (for example) Royal Navy ships can be ready, and forces can deploy with sufficient weapons to last more than a few days. Details on the new ‘long-range’ weapons announced in the SDR, and the factories to produce them, should be a start.
• Personnel. If people are Defence’s ‘most important asset’ then accommodation, training, pay and conditions (particularly critical for the continued function of the Royal Fleet Auxiliary) will be important for keeping personnel numbers up and addressing loss of experience.

• Prioritisation for transformation. It is unlikely there will be a full description of the new size and shape of the Armed Forces, akin to the kind of ‘order of battle’ seen in previous defence reviews. But by highlighting the profile of the spending (in which years it is allocated) and priority areas for investment, the balance of older and newer capabilities and technology (such as uncrewed systems, processing power and artificial intelligence) will become clearer, as well as the concepts to be supported.
• Enablers. If technological transformation will underpin more effective Armed Forces, then the weight given in the investment plan on enablers alongside ‘teeth arms’ matters. Areas to watch include space-based capabilities (both communications and surveillance), intelligence, transportation and the so-called Digital Targeting Web, all of which are needed to move, support and inform whatever firepower the military wants to bring to bear.
• Compromises. The plan must ultimately make clear what capabilities and being retired early, cut or replaced, and what any replacements will be (or where gaps will exist), to provide assurance that a coherent force is being created, and make note of activity that will have to stop. Magical calculations that are based on ‘more with less’ fall in the category of traps that must be avoided.

On that score, there are a number of traps from past reviews, equipment plans and proposals that need to be avoided if the DIP is to be credible and useful.

• Service politics. The Single Services and UK Cyber & Specialist Operations Command (CSOC) all have different needs and are supposed to be working towards the idea of an ‘Integrated Force’. If it transpires the increases in investment are somehow mysteriously equal, and ‘pain’ is also equally spread, then it is probably an indication compromises have been made over the eventual shape of the military that will lead to a muddled strategy and incoherent force.
• Cash categorisation. While the last Spending Review did result in an increase of several billion pounds per year for Defence, it was notable almost all of this was in capital (CDEL), rather than resource spending (RDEL). The former mostly represents one-off costs of acquisition while the latter provides the day-to-day running costs for people, capabilities and facilities. If there is new funding, but it all manifests as CDEL, then the military will be buying capabilities it cannot sustain or run.
• The mirage of efficiency. Any large organisation involves waste, and the MOD is no exception. But it is also addicted to what a former CDS has called ‘whimsical’ if not ‘delusional’ assumptions about so-called ‘efficiencies’, thus over-loading spending with money that does not yet exist. This doomed the 2015 SDSR, in particular, and therefore any savings plan needs special scrutiny.

• Profile. The profile – in which years the spending is allocated – will also need scrutiny to avoid the trick whereby money is allocated too late to be useful, after tight early years which necessitate cuts. This also applies to estimates of where contingency funding is allocated. Previous Equipment Plans consistently allocated contingency funding in the very late years of a ten-year plan, which meant the freedom neither prevented cuts in early years, nor ever materialised.
• Nuclear. The nuclear portfolio involves more than just the Deterrent, also encompassing the attack submarine fleet, the disposal of older nuclear-powered submarines, and various facilities. Spiralling costs on Dreadnought and potential new nuclear weapons are estimated to be heading towards nearly 25% of the defence budget in the period to be covered by the investment plan, so it needs to be able to give confidence nuclear will not continue to erode budgets elsewhere.

Get Used to Disappointment

None of this has actually identified the number of ships, armoured vehicles or drones ‘required’ or discussed what the defence budget ‘needs’ to be based on these requirements. That is because the details of the true costs of defence, and the level of investment needed have been lacking for some time. Attempts have been made to total up a bill for implementation of the SDR, but without understanding what current gaps really are in the programme, it is difficult to know what £28 billion, £15 billion or any other figure in between will actually achieve. However, we can infer that if there were not significant problems in defence defining its requirements and the associated costs, the Investment Plan would have been published by now. That it has not suggests the rationale for change, the scale of change or the costs of change have not been agreed across government, which bodes ill for a country attempting to put itself on a ‘war footing’ to deter future conflict.

© RUSI, 2026.

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