Former foreign minister Gareth Evans has said AUKUS will prove to be one of the worst defence and foreign policy decisions ever made by an Australian government, and that Donald Trump is only permitting the deal to destroy Chinese nuclear threats to the US mainland. This was reported by Qazaqyia.kz citing The Guardian.

In evidence to an independent public inquiry into the $368bn nuclear agreement with the US and UK on Thursday, Evans, a cabinet minister in the Hawke and Keating governments, warned that the transfer and construction of submarines to Australia from the early 2030s is effectively only an extension of the American military fleet. He said a future US administration would not come to Australia's aid in the event of an "existential attack" and would only assist in a military conflict if its own assets on Australian soil are threatened.

"The notion that extended nuclear deterrence justifies our prostration – that the US really would be prepared to sacrifice San Francisco for Sydney, let alone Miami for Melbourne – is, and always has been, a ludicrous delusion," Evans said.

Foreign affairs minister from 1988 to 1996, Evans told a hearing in Melbourne that the delivery of three Virginia-class submarines from the US starting in 2032 is unlikely, due to construction delays and shortages for the US fleet, and that five new-design SSN-AUKUS attack submarines to be jointly built by the UK and Australia will be extremely difficult. He said the complexity and timeline of the second phase of AUKUS requires even more "heroic levels of optimism" than is needed for the American vessels.

"Every report coming out of the UK indicates that its defence-industrial base is presently under extraordinary stress, with submarine building schedules tightening and costs increasing, and with every prospect of further deterioration, notwithstanding Australia's commitment to spending $4.5bn over 10 years to help boost production rates," Evans said.

Evans called the government's expected price tag for the deal "wholly speculative" and said the US views the submarines as primarily supplementary assets, effectively embedded into US military command, for the task of finding, tracking, attacking and destroying Chinese submarines seen as posing a risk to the US mainland. "Australian ministers have never explicitly conceded as much but the conclusion is inescapable that from the outset the whole enterprise has been viewed through an alliance reinforcement lens, with this role for the boats being the understood quid pro quo."

Evans called AUKUS a doubling down on Australia's commitment to the US alliance, painting a target on the country's back in the event of a military conflict. Thursday's first hearing of the public inquiry – which is not a parliamentary process and is being backed by trade unions and the Australian Peace and Security Forum – was led by commissioners including former Labor minister Peter Garrett and former defence boss Chris Barrie. Current Labor ministers have accused the inquiry of being anti-AUKUS from the outset.

Nuclear non-proliferation campaigners Tilman Ruff, Richard Tanter and Dave Sweeney gave evidence in the hearing, as well as retired diplomat John Lander. Highly sceptical of the AUKUS agreement, the inquiry's commissioners will hold public hearings around the country before delivering a report in October.

Foreign minister Penny Wong said on Thursday she and defence minister Richard Marles had discussed AUKUS with their UK counterparts in regular talks overnight. The UK government has confirmed the first steel for the newly built joint submarines will be cut next year, even as Britain's existing submarine program runs years behind targets and billions over budget.

"This submarine capability is central to assuring Australian sovereignty in a much more contested world," Wong said. "It is a capability we need in a world that is more contested. There is no doubt that this project has its challenges. There is no doubt it is ambitious. But there is also no doubt that we do need this capability to assure our interests. And we are very focused on delivering it."

Labor is pushing back on criticism of the plan, including from its own MPs, before the party's national conference in Adelaide next month.