The Aukus programme will be "a disaster" if it goes wrong, former defence chiefs have warned.
Caution was sounded in Parliament after this week's summit in San Diego, California, where Prime Minister Rishi Sunak, US President Joe Biden and Australian Prime Minister Anthony Albanese set out details of the latest stage of the Aukus partnership, a deal between the UK, US and Australia to develop a new generation of nuclear-powered submarines.
Former UK military bosses highlighted the recent "woeful" performance of defence giant BAE Systems, which will be a central player in building the UK's vessels at Barrow-in-Furness, Cumbria.
Ministers were told industrial inefficiency in the programme would "need to be dealt with swiftly and ruthlessly".
Under the Aukus agreement, intended to counter China's increasing military assertiveness in the Pacific, Australia will get its first nuclear-powered submarines.
It will also provide the Royal Navy with replacements for its seven Astute submarines, potentially doubling the size of the fleet of its attack boats, but the vessels will not be nuclear-armed.
Speaking at Westminster, Lord Stirrup, former head of the Armed Forces, said: "The Aukus programme, if executed well, will be very good news for this country.
"If executed badly it could be a disaster."
The independent crossbencher argued the performance of BAE Systems in recent years had been "pretty woeful".
He added: "It is not, of course, for the Government to run private companies but industrial performance in this programme will be of strategic importance to this country.
"Could I ask the minister what long-term mechanism and processes are in place to monitor and audit industrial performance and what leverage they will have over the industries concerned?
"Industrial under-performance in this programme will need to be dealt with swiftly and ruthlessly. Something that has not happened before," he added.
Lord Stirrup also stressed the need to have a sufficient skills base to deliver the "ambitious" programme.
Responding, defence minister Baroness Goldie pointed out it was a trilateral agreement, saying: "There is, therefore, a triumvirate interest in ensuring that nobody is slipping, that everybody is keeping up to the mark."
Steps were already under way to boost skills, she said.
Former Royal Navy chief and Labour peer, Lord West of Spithead, said: "This is a very brave and bold decision and I am delighted it has been made because we are in an era where we need that.
"Having said that, there are real problems within our submarine world. The performance by BAE Systems has not been good."
He stressed the importance of one person being in charge with direct access to the Prime Minister so they could "chop people's legs off if they weren't doing what they were meant to".
Lord West added: "Because if it goes wrong, my goodness me, it is going to be a disaster."
Lady Goldie said: "There will be a need to have a very robust assessment kept on this programme.
"With three eyes focused on what we are trying to deliver then there's almost a third leg to the protection of that robust surveillance of the contract."
Labour former defence secretary Lord Reid of Cardowan pressed the Government over the absence of costs, asking: "What is the realm of possibility on which this decision was taken?
"It cannot be taken without ministers having any idea at all on how much it is going to cost."
Lady Goldie said: "I am slightly disappointed at Lord Reid's rather despondent demeanour."
While unable to give "a precise figure", arguing it would depend on a number of factors, she told peers: "I think this has been universally regarded as one of the most important and exciting announcements for UK defence and for our naval capability that we have seen in decades.
"This is a hugely important development.
"I have no doubt whatsoever that the Government has made the right decision to proceed with this," she added.