Just a query, I believe one of the likely subs that Australia will choose to acquire will be the US Virginia Class which is an SSBN
No, the Virginia class are hunter-killer SSNs, the USN current SBNs are the Ohio class.
Early block Virginia class boats had 12 vertical launch tubes for conventional tomahawk cruise missiles. The block 3 boats replaced these with larger vertical payload (VLP) tubes able to carry up to 7 tomahawk or other payloads such as SF UAVs for infiltration etc. From from 2025 onwards 9 of the last block will be stretched versions including a VPM module containing another 4 VLPs, increasing their conventional firepower
This isn’t an innovation - the USN has 4 SSGN boats (modified Ohio class) do the same job, but those will, presumably, be retired at the same time as the SBN boats are replaced boats are being retired and replaced by the Columbia class from 2029 onwards.
The USN do not currently have a nuclear cruise missile, so no possibility of the new boats carrying nuclear weapons.
The USN are developing a new nuclear cruise missile, to enter service in about a decade. At which point they will be able to deploy them on their block 3-5 Virginia class boats if they wish.
Whether Australia will buy Virginia class boats and whether they would have any VLP/VLM is something I am sure will be a matter for discussion - but of course cruise missiles can be fired from conventional torpedo tubes, as the RN has amply demonstrated, so the point is moot except for regards the total number able to be carried.
In the meantime there has currently been no suggestion of Australia considering acquiring nuclear weapons.
http://submarinesuppliers.org/wp-con...ia-Payload.pdf
https://en.wikipedia.org/wiki/Ohio-c...GN_conversions