Having spent much of his naval career as a submariner,including extended periods aboard both nuclear-powered and conventional diesel vessels,Hammond said he had “lived and breathed” submarines for most of his adult life.

“The net sum of my experience and analysis of the contemporary and future operating environment leads me to the conclusion that only the nuclear-powered submarine capability of the type we’re about to invest in is the appropriate investment for this nation going forward,” Hammond said.

Hammond,who was appointed head of the navy last June,said submarines served a broader purpose than simply defending the Australian coastline from possible invasion,a scenario emphasised byformer prime minister Paul Keating in his criticisms of the plan.

“Our maritime domain is significant;we’re not parked at the edge of an international waterway,” Hammond said. “Our interests lie across the Indian Ocean and throughout the Pacific Ocean.”

While critics such as former senior Defence official Hugh White have argued Australia should acquire a larger fleet of diesel-powered submarines,Hammond said a “tipping point” would be reached some time in the 2030s or 2040s when these vessels could be rapidly detected and attacked when they rose to the surface to recharge their batteries.

Nuclear-powered submarines,by contrast,can remain underwater for months at a time,making them harder to detect.

‘We are vulnerable to the interruption and disruption of sea lines of communication and seabed infrastructure,and we’ve seen both of those play out in the Ukraine conflict.’

Vice Admiral Mark Hammond

“I’m glad we’re a nation that recognises that and is prepared to make the tough decision to spend a significant amount of national treasure on a capability that will remain absolutely relevant for many decades to come,” he said.

The government’s plan will see Australia buy up to five Virginia-class nuclear-powered submarines from the United States before it constructs a fleet ofeight nuclear-powered “AUKUS class” submarines,based on a future British design,in Adelaide.

Hammond said he vividly remembered the hand-wringing about the development of the navy’s current Collins-class submarines,a unique Australian design,in the 1990s.

Although derided as “dud subs” at the time,he said the Collins-class boats were now widely regarded as some of the world’s best conventional-powered submarines.

“I’m wary of repeating the cycle that this is so complex,it’s too hard,it’s beyond our nation. We’ve built submarines before;we’re going to build them again,” he said.

“I don’t think we should repeat the mistakes around the hand-wringing of the Collins program. We should embrace the challenge and the opportunity that lies ahead.

“From where I sit,the national psyche should be proud of its track record of tackling complex challenges and setting global standards. The Snowy Hydro program is a shining example of that.”

Hammond said it was a “red herring” to argue that nuclear-powered submarines could make Australia less safe because the United States would want to deploy them in a potential conflict with China over the self-governing island of Taiwan.

“We’re not changing the range and scope of our operations;we’re changing the propulsion system that enables those operations,” he said.

As forthe argument advances in undersea detection technology could render the submarines useless,he said:“If the pundits are to be believed that the oceans are going to be transparent,they’re being ignored by every navy on the planet. It seems to me that everyone who can afford to build submarines is building submarines – you just have to look at the proliferation in our own region over the past 25 years.”

He said developinga fleet of nuclear-powered submarines was “not something you can turn on at the last minute”.

“You either have a potent submarine capability or you don’t,” he said.

In the short term,he said his priority was the life-of-type extension of the current Collins-class fleet.

“It would be very easy to be seduced by the nuclear program of tomorrow;we’ve got to keep our eye on the conventional capability of today,” he said.

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