A naval defence expert has called for calm after critics trashed Canberra’s plan to buy three second-hand Virginia-class submarines from the United States.Former Royal Australian Navy officer Jennifer Parker said the move would simplify operations and ensure the high-tech kit is in Aussie seas sooner.At the weekend, Defence Minister Richard Marles announced the government was scrapping plans to buy at least one new Virginia-class sub under Pillar I of the AUKUS defence pact. The government was meant to purchase two used subs and one new in the 2030s but is now electing to buy all three second-hand subs.Speaking with news.com.au, Ms Parker said though it was never clear what capabilities the new sub would have had, it certainly wouldn’t have included an increased missile payload, known as the Virginia Payload Module, because it was too expensive to install.“We don’t need to have the best of every capability. We need to get ourselves into the nuclear-powered submarine game as a priority. We don’t need to have the best of the best. The current block four nuclear-powered nuclear submarine is way better than any other attack submarine in the world right now and it will still be in the 2030s when we get it,” she said.The defence expert said the used fleet would not need to be decommissioned until 2058, giving AUKUS allies suitable time to develop a new fleet of nuclear subs known as the SSN-AUKUS.“That is a long time from now and so much can change in terms of technology. We should have built SSN-AUKUS by then,” Ms Parker said.Ms Parker added buying three identical subs would drive down costs because Canberra would save money in training and maintenance expenses.She also said using new subs requested a longer “lead time”. “It comes with more trails introducing it, making sure it’s safe for sea; a longer lead time to becoming operational,” she said.“Yes, the downside is there is less life [in the used subs] but the upside is there is reduced risk.”‘The first crack in the dam’Former South Australia senator Rex Patrick said the decision to buy three used subs was “a coming of truth”.He told 2GB’s Ben Fordham: “For the past three years, anyone who has bothered to look into the US submarine industrial base has known that we were never going to get Virginia-class submarines for the Royal Australian Navy. This is the first crack in the dam and what a very expensive facade.”The former submariner said there was “no pathway” to boost the US’ submarine building capacity to the 2.3 ships per year required under the AUKUS agreement. He said shipbuilding was stuck at a stubborn 1.1 subs per year.He also claimed Australia has spent $2.8bn boosting the US’ submarine building capacity and there was no way to claw that money back.“There’s just bad news sitting in all of this. It’s not something to someone paying attention is surprised at,” he said.Ms Parker said questions about the US’ sub building capacity were a “different conversation” and said Australians should view the funds being spent as a “downpayment” on a future sub.“Remember the end state of AUKUS is not three Virginias in the 2030s. The end state is the US, UK and Australia increasing their submarine industrial capacity by being able to build submarines in all three countries. The Virginia-class in the 2030s is just a stop-gap. Think of the crawl, walk, run analogy. It’s the walk the analogy to get us into the nuclear game before we start producing our own,” she said.Ms Parker said the US may still choose to sell Virginia class subs to Australia even if it doesn’t meet its own shipbuilding goals, adding Western navies are shifting their focus to develop new underwater unmanned drone capacity.“It’s 2026 right now. We are investing in those two submarine industrial bases. AUKUS continues to be on track. This conversation has become, in many ways, of what ifs and if we don’t know the answer to every single what if now, it’s obviously a failing. That doesn’t make a lot of sense.“If we got to the 2030s and Australia did not get submarines from the US, then there would be a discussion about what the financial implications are and they would have a conversation around that. That is not where we are.”On Saturday, Marles told reporters at the IISS Shangri-La Dialogue in Singapore that Australia would no longer buy any new submarines but purchase three second-hand subs from the same production block. He said the move would simplify Australia’s naval fleet. “We had the prospect … of almost having four classes of submarines operating at the same time: the last of the Collins Class, two in-service Virginias, a brand new Virginia, and a brand new SSN-AUKUS. That gets pretty complicated,” he said.“What we will have here is a simpler pathway. The Virginias we are acquiring will all be of the same type and I can’t overstate the significance of that.The AUKUS defence treaty, struck between the US, UK and Australia – much to the chagrin of France – promised Canberra eight state-of-the-art nuclear-powered submarines, called SSN-AUKUS, by the late 2030s. Some would be built in Australian shipyards.Under the agreement, Canberra would get three to five of the older subs while the SSN-AUKUS class is being built.