The Public Accounts Committee says the government's delay in publishing the Defence Investment Plan has harmed the UK's credibility with allies and risks raising procurement costs. The PAC highlights safety and readiness concerns—notably problems with Ajax armoured vehicles that affected 33 soldiers—and flags rising nuclear spending, including Dreadnought submarines estimated at £31bn and a £6.1bn accounting discrepancy. The report issues six recommendations demanding clearer timelines, better supplier mitigation and greater transparency on nuclear expenditure.
MPs Warn Delay To Defence Investment Plan Has Damaged UK Credibility
British Army soldiers on exercises in Finland with a drone [PA Media]
Delays to the government's long-awaited Defence Investment Plan (DIP) have, the Public Accounts Committee (PAC) warns, undermined the UK's credibility with allies and risked driving up the cost of military procurement.
PAC: Delay Risks Higher Costs And Weakens Deterrent
The DIP, originally expected in the autumn, is now due to be published shortly before a Nato summit early next month. The PAC says the hold-up will increase procurement costs for new equipment and "hinder the government's attempt to modernise the Armed Forces."
The committee found the delay was largely attributable to a lack of firm decisions within the Ministry of Defence (MoD) about which capabilities, infrastructure and personnel are needed to make the Armed Forces warfighting-ready.
"From the committee's point of view, the nation has now in fact gone years without a credible plan for UK military capability," said PAC chair Sir Geoffrey Clifton-Brown MP. "Excuses to the effect of 'taking the time to get the details right' simply do not cut it."
MoD Response
An MoD spokesman said the DIP would "fix the outdated, overcommitted and underfunded programme we inherited" and that officials were "working hard to finalise it." The ministry also highlighted that, since the government took office in July 2024, it had signed more than 1,400 major defence contracts and was delivering "a generational increase in defence spending."
Concerns Over Specific Programmes
The PAC report flagged ongoing problems with the Ajax armoured vehicle programme. In November 2025 the army paused use of Ajax vehicles after soldiers reported being made unwell by noise and vibration; some personnel vomited after leaving the vehicles. The PAC found that 33 soldiers had been affected in total and five were still under medical review as of March.
The committee criticised MoD instructions for soldiers to carry out maintenance checks every time they stopped the vehicles as "unreasonable" in the context of sustained operations, and asked the MoD to explain how current operating restrictions were realistic and operationally appropriate.
"With an Ajax 2 package of upgrades now in development at an unknown cost, the PAC awaits to see, more in hope than expectation, whether these endeavours will succeed," the report says.
The Ajaxes currently deployed are for trials only. The government is proceeding cautiously and recognises it must rebuild confidence in the vehicles before placing them into full service.
Rising Nuclear Costs And Accountability Concerns
The PAC also expressed alarm at the level of nuclear expenditure and a lack of transparency. The MoD spent 18% (£10.9bn) of its defence budget on the UK's nuclear deterrent in the most recent accounts; the committee warned this share could rise to as much as 25% in coming years.
The UK is building Dreadnought-class submarines to carry Trident missiles at an estimated cost of £31bn. The report noted recent failures in tests of US-made missiles and called on the MoD to provide Parliament with clearer cost and performance data for the nuclear programme.
Separately, the PAC said the MoD's accounts showed a £6.1bn discrepancy it described as "a completely unacceptable failure to maintain accounting records to support £6bn+ of assets." The MoD has indicated this relates to how payments over the past 15 years should be recorded in current accounts.
Submarine Readiness
The Mail on Sunday reported that all five Royal Navy Astute-class attack submarines were awaiting repair work and temporarily unable to sail. The MoD responded that "strengthening and sustaining our submarine capability is a top priority" and said British waters are protected by a range of assets including warships, patrol aircraft and submarines.
PAC Recommendations
The PAC sets out six specific requests for the MoD:
- Write to the committee within three months explaining how the DIP will be used in light of changing international threats.
- Explain how it is mitigating the impact on suppliers caused by the delayed publication of the investment plan.
- Specify when Ajax can be made fit for purpose and how that will be achieved.
- Demonstrate how the 2025–26 financial statements are supported by accurate accounting records.
- Identify initiatives to improve recruitment for the Armed Forces.
- Set out how and when it will routinely provide Parliament with detailed cost and performance information on the nuclear enterprise.
The PAC warns that continued delays or opaque accounting will harm the MoD's standing with industry and allies and could increase costs at a time of heightened geopolitical instability.
What Happens Next
The DIP's imminent publication should clarify the MoD's investment priorities and timelines. The PAC's report makes clear it will hold the department to account and expects prompt, specific responses to its recommendations.
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