AUKUS Subs Main Role Related to Nuclear War

Marine Engineer, Professor Jonathan Gates authoritative 188 page UK publication: 

Astute Class Nuclear Submarine: 2010 to date (Haynes Owners' Workshop Manual, 2018).

On page 159 Gates indicates the most important missions of Astute submarines (and by extension SSNs generally):

"Astute class submarines have a major role in ensuring that SSBNs are not followed in peacetime and are protected in wartime. 

They are also responsible for tracking enemy SSBNs and neutralising them in times of war."

All navies that have SSNs see their SSNs' major role as protecting their own nuclear missile armed SSBNs while being prepared to destroy enemy SSBNs. 

Following Australia's policy of Collins SSK interoperability with US SSNs escalating in the 2030s to Australian SSNs becoming "interchangeable" with US SSNs:

1.  Where does this leave Australia? Australia's intention is to acquire a large fleet of 8 SSNs for a "small-medium" power, while having no public plans to acquire SSBNs.

Or will Australia become an ally in nuclear war fighting...

2.  Might the Australian Government's insistence that "Australia's AUKUS SSNs will be conventionally armed" disguise roles of protecting US SSBNs in wartime while destroying Chinese SSBNs in wartime? 

3.  Will future non-nuclear Tomahawk cruise missiles for Australian SSNs be gradually replaced by a new class of weapon. That is by US developed nuclear armed hypersonic missiles for Australian SSNs in the 2040s?