Britain’s flagship £3.5billion aircraft carrier has broken down again as ministers wrangle over boosting defence funding.

HMS Prince of Wales, which has been plagued by problems since entering service, was forced into port in Norway for repairs, delaying her departure for the celebrations marking the 250th anniversary of the US Declaration of Independence.

A senior naval source told the Daily Mail the carrier’s latest travails were ‘devastating for morale’. 

It comes as Keir Starmer faces mounting pressure to publish a delayed review into boosting defence spending, which is due next week.

But rows with the Treasury over money could force another postponement after a year of delays.

Military chief Sir Richard Knighton warned on Thursday of the need to enhance our defensive capabilities as Russia was ‘raising the stakes’ and ‘risks crossing the line’.

On Thursday, Sir Keir pledged the long-delayed Defence Investment Plan (DIP) will finally be published in the next month – as he revealed British intelligence believes Russia could attack a Nato country by the end of the decade.

He told LBC: ‘We do have to be ready, and I’ve always argued that deterrence is the best way of avoiding war, but to deter, you have to be ready, and that’s what this is all about.

HMS Prince of Wales has broken down as ministers wrangle over boosting defence funding

‘Our intelligence and the intelligence of other countries is that Russia could attack Nato as early as 2030, so that is why we need to be ready.’

Sir Keir said it was his ‘first duty’ to ensure the country can protect itself from attack.

And he warned that spending cuts could be needed in other areas to fund defence spending.

Ministers have been warned of a £28billion black hole in defence spending plans, but the Treasury has deemed this to be unaffordable. Chancellor Rachel Reeves is trying to chisel a compromise figure of £18billion down to £15billion.

But despite the looming deadline, multiple government sources said the funding for the package is still not agreed.

Air Chief Marshal Sir Richard said Russia was ‘probing, challenging, testing our defences’ including through ‘cyber attacks or trying to smuggle technology and reckless sabotage and assassination attempts’.

The Chief of the Defence Staff said: ‘In my 35-year career, this is the most dangerous period that I have known. 

As a consequence, it is important that we enhance the capability and the readiness of our Armed Forces alongside our allies to deter our adversaries from doing something daft.’

The Prime Minister has pledged the long-delayed Defence Investment Plan (DIP) will finally be published in the next month

The latest breakdown of Britain’s most powerful warship is its most embarrassing yet because it is due to take part in Donald Trump’s celebrations. 

The US President and his defence secretary Pete Hegseth have mocked the Royal Navy as ‘old and broken down’ in recent months.

Last night, defence sources acknowledged a ‘minor technical issue’ had been identified which required the 65,000-tonne carrier to dock in Stavanger.

The mechanical issue is understood to involve the propeller shaft – a recurrent problem for Prince of Wales and her sister ship HMS Queen Elizabeth – though this has not been confirmed. 

According to the carrier’s account on X, engineers and logisticians were working ‘tirelessly’ to ‘deliver effective maritime support’.

No details have been released publicly about the fault that was identified on a vital Nato exercise in the High North.

A navy source added: ‘With morale already rock-bottom over defence spending and delays over the DIP, the last thing the Royal Navy needed was HMS Prince of Wales marooned in a Norwegian fjord. 

Then, to rub salt into the wounds, it appears the breakdown has been caused by the recurrence of a previous problem.

‘Crucially the Royal Navy signed off for responsibility for the maintenance of its carriers from the manufacturers without confirming the carriers were entirely seaworthy. So every time there is an issue with the propellers, the taxpayer picks up the tab.’

In 2024, HMS Queen Elizabeth was withdrawn from a Nato exercise because of propeller issues. 

In 2022, HMS Prince of Wales broke down on the way to joint exercises with the US Navy and the Royal Canadian Navy and had to be towed back to harbour.

The Ministry of Defence said on Thursday: ‘HMS Prince of Wales is currently conducting a port visit to Stavanger.

‘We expect her to set sail in the coming days.’