The Virginia-class nuclear powered submarine USS Minnesota arrives at the US Naval Base Guam, on 26 November 2024. Photo: US Navy/ Justin Wolpert
A report to the US Congress discusses the possibility of an accident with a nuclear-powered submarine if it supplies one to Australia.
This comes amid renewed questions over whether an AUKUS submarine deal would leave the US vulnerable, and an accident off the English coast where a tanker carrying jet fuel for the US military has hit a cargo ship.
The risk of a marine accident is one of three risks looked at around the submarines deal that is central to the the AUKUS Pillar One pact.
The congressional research report said an accident "might call into question for third-party observers the safety of all US Navy nuclear-powered ships".
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That could erode US public support and the ability of US nuclear-powered ships to make port calls around the world.
The 111-page report by the Congressional Research Service discussed the US not handing over the subs at all - although Canberra just made a $870m downpayment on them.
Keeping them might make up for the US sub fleet hitting "a valley or trough" around now till the 2030s, and shipbuilding being at a low point, it said.
Donald Trump's pick for the top defence policy role at the Pentagon, Elbridge Colby, has said AUKUS could leave the US short and "it would be crazy to have fewer SSN Virginia-class [attack submarines] in the right place and time".
The USS Vermont, a Virginia-class SSN - nuclear powered submarine - in the Thames River, Connecticut, on 26 October, 2020. Photo: US Navy/ John Narewski
The new research report to Congress said Pillar One was launched in 2021 without a study of the alternatives.
One alternative "would keep all US-made SSNs under the control of the US Navy, which has a proven record extending back to 1954 of safely operating its nuclear-powered ships".
The original Pillar One pact is for the US to sell between three and five subs to Australia, then Australia to use US and UK nuclear propulsion technology to build another three-to-eight nuclear powered, conventionally armed submarines itself, for a total fleet of eight.
Australia's Defence Minister Richard Marles said on Monday that Elbridge Colby was broadly supportive of AUKUS, if enough subs were available.
Canberra was aware of the challenge in the US around producing submarines, "and that's why we're contributing to the US industrial base".
"And it's a significant contribution and it's going to increase the availability of Virginia class submarines for the United States.
"That's a point which has been accepted and understood by the US Defence Secretary, Pete Hegseth, in the meeting that I had with him."
Australia was last year included as a "domestic source" of US military production for the first time, and is aiming to ramp up making ammunition and missiles, as well as test hypersonic weapons with the US and UK.
"That's going well in the sense that we are making the contributions, we are seeing an increase in production rates, and over the time frame in which we are looking to have our Virginia class submarines transferred to us, we are confident that this challenge can be met," Marles told the ABC.
In the US, Trump appears most focused on building an 'Iron Dome' missile defence system, as he mentioned in his speech to Congress. This would be another huge pressure on military spending.
The report to Congress covered three big risks - accidents and whether Pillar One was the best option for deterrence and "warfighting cost-effectiveness", and how the tech - the "crown jewels of US military technology" - could be kept secret, especially from China.
It debated a different "military division of labour".
"Australia, instead of using funds to purchase, build, operate, and maintain its own SSNs, would instead invest those funds in other military capabilities - such as ... long-range anti-ship missiles, drones, loitering munitions, B-21 long-range bombers, or other long-range strike aircraft" to conduct "missions for both Australia and the United States".
The general rule was programmes should not go ahead without a sound business case, it noted.
"There is little indication that, prior to announcing the AUKUS Pillar 1 project in September 2021, an analysis of alternatives ... or equivalent rigorous comparative analysis was conducted to examine whether Pillar 1 would be a more cost-effective way to spend defence resources for generating deterrence and warfighting capability".
The report made no mention of how New Zealand, Japan, Korea and others might join AUKUS Pillar Two, an agreement for sharing advanced military tech.
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