Weapon purchase is always procured to meet the the relevant threat.
What is the threat in this case?
Indonesia gonna invade? If 250 million Muslims on Australia doorstep is seriously about occupying Australia, 8 nuclear subs is a terrible choice to operate in coastal geography around Australia, they're bigger and louder than electric engines in shallow waters.
S o nuclear subs must be deployed in places far away from Australia to be most effective. So who else is threat?The answer to that is obviously whoever US views as THEIR threat, in this case China or Russia. Therefore the subs will be used against China and Russia in their territory undetected. The subs are clearly not used defence, but for offensive operations to support US interest. This is just self evident.
