WASHINGTON - Defence Secretary Pete Hegseth sought on June 10 to reassure lawmakers over the US pledge to supply Australia with a fleet of nuclear-powered submarines, amid growing concern that production is not rolling out quickly enough to meet the commitment.

Under the Aukus deal signed to great fanfare in 2021, Washington, London and Canberra are cooperating on the joint development of cyber warfare tools, artificial intelligence and hypersonic missiles.

The agreement commits the US to building cutting-edge submarines for Australia, an investment with an estimated cost of up to US$235 billion (S$300 billion) over 30 years.

Australia plans to acquire at least three Virginia Class submarines from the US within the next 15 years, eventually manufacturing its own nuclear-powered subs.

The US navy has 24 Virginia-class vessels, which can carry cruise missiles, but American shipyards are struggling to meet production targets set at two new boats each year.

Critics question why the US would sell nuclear-powered submarines to Australia without stocking its own military first.

Questioned by members of the US House of Representatives, Mr Hegseth said his team was talking “every day” to US shipbuilders Electric Boat and Huntington Ingalls to ensure that “their needs not only are being met, but their shortfalls are being addressed.”

The former Fox News host, one of President Donald Trump’s most divisive Cabinet appointments, acknowledged a “gap” between current supply and future demand, but added that submarine building is “crucial” to US security.

He blamed Mr Trump’s Democratic predecessor, Mr Joe Biden, for having “neglected” the industrial base for submarine construction.

While the stealthy Virginia class is an attack and intelligence gathering submarine designed for a wide range of missions, the Columbia class is a ballistic missile carrier built for nuclear deterrence that will be the largest submarine ever built by the US.

Democrat Rosa DeLauro – whose home state of Connecticut builds Navy submarines – berated Mr Hegseth over the Pentagon’s decision to move US$3.1 billion earmarked in 2026 for Columbia-class construction to 2027 and 2028.

“Is that going to raise alarm bells across the defence industrial base by signlaling a l...