The US is confident its world-leading nuclear submarine technology being handed to Australia will stand the test of time as China and Russia work to outclass the West.
But concerns remain about the pace at which Beijing is powering ahead with nuclear technology investment as Canberra teams up with Washington and London to develop next-generation artificial intelligence and quantum technologies.
Australia will purchase nuclear-powered submarines from the US in the next decade before a new class of submarines is brought in through the trilateral AUKUS alliance, which also includes the UK.
Undersea capabilities remain "a comparative advantage of ours", a US defence department undersecretary says.
"The secret sauce of AUKUS, of course, is that you've got three tremendously capable countries that would be operating very capable submarines," Dr Mara Karlin said.
"The US military is the strongest military in the world and it is also the strongest military that we have seen in history, I feel pretty confident about our undersea capabilities ... so I'm not terribly worried."
Following a suspected Russian sabotage of an undersea communications cable in the Baltic, Dr Karlin said a number of countermeasures were being worked through.
A particular emphasis is being put on underwater drones but she would not go into details, except to say "we have a robust and sophisticated undersea capability".
Australia is investing billions to bolster the US industrial base and ensure it has the capacity to build and maintain its submarine fleet while selling three to five Virginia class subs to Canberra.
White House investment in manufacturing is already reaping dividends with submarine availability jumping from 60 per cent to 67 per cent in the last few months, Dr Karlin said.
"We both want to increase the number of submarines that we can produce but we also want to make sure that the submarines we have, we're actually able to use."
But there have been "worrisome steps by China in terms of its technological investments", particularly around modernising and diversifying its nuclear arsenal, Dr Karlin added.
Asked about analysts' concerns that expanding the US military presence could make Australia a target for China or another adversary, Dr Karlin said it was incumbent on all nations to work together to maintain peace in the region.
The two militaries which had worked together for decades would continue to do so to tackle any challenges, she added.
There have been nearly 200 "unsafe and unprofessional" incidents targeting the US military by China since 2021, and about 100 more targeting its allies and partners.
Although no conflict with China was imminent or inevitable, the top priority remained on sustaining and strengthening deterrence against Beijing, the undersecretary said.