Public trust has been achieved in communities across the nation but it's an ongoing job that requires "constant nurturing", Richard Marles told the Submarine Institute of Australia conference in Perth on Wednesday.
"People's heads are in the right place," he said.
"People do have a sense of anxiety that the world is a pretty complex and volatile place.
"That is how I would describe the mood of the nation, and that does give a basis upon which you can then provide a narrative about why we would be spending a very considerable amount of money on this particular platform."
Mr Marles said Australia was providing submissions for the US AUKUS review and was "fully across" its process and timing.
The review should "pull no punches" about areas where improvement could be achieved, he said.
"Obviously there are areas where we would like to be going faster than we are," he said.
"It would be extraordinary to be standing up here and saying everything is tickety-boo.
"Things are pretty good, like I really think the glass is more than half full, but there is absolutely room for improvement."
Australia continues to take significant, groundbreaking steps in preparation to receive, build and operate nuclear submarines, but the timeline was tight, he said.
"I'm acutely aware that a milestone missed now cascades into other milestones becoming much further delayed down the track," Mr Marles said.
"So there's a relentless focus right now to make sure we are not letting any milestones slip."
The trilateral security pact between Australia, the UK and the US to supply nuclear submarines at an estimated cost of $368 billion has been slammed since it was announced in March 2023.
Former prime ministers Malcolm Turnbull and Paul Keating and former Labor foreign minister Gareth Evans are among those who have criticised the deal amid ongoing protest across the nation.
The Australian Greens also oppose the pact, along with the members of the Australian Anti-AUKUS Coalition, which is made up of peace, community, environment, social justice, independence, faith and socialist organisations and unions.
