I can understand deterrence but am not sure who they’re meant to be deterring.

Australia’s closest neighbours are Indonesia and PNG. PNG is a military non-entity (2,000 strong defence force with no Navy or Air Force).

Indonesia’s military is poorly equipped, poorly organised, relatively unprofessional and mainly serves a garrison force in the multitude of. Even at it’s peak in the early 1960s it was not a capable force. It is weaker than Singapore or Thailand.

None of the other SE Asian countries have the capability to threaten Australia. Most Pacific states don’t even have militaries comparable to PNG and NZ’s force is a peace keeping force only with no offensive capability.

12 submarines are not going to be deterring China or India who are full fledged nuclear powers and who by the time the 12 new subs come on line (2030-2040) will be able to turn Australia’s cities into glass car parks with the flick of a switch (Chinese can already do it).

You’re sidestepping the most likely scenario; the one that was the reality of WWII. Are you from NZ or the UK?

As for nuclear weapons, its hard to see what any nation would gain from using nuclear weapons unless they could be 100% certain that the there would be no retaliation. And what would they gain, a radioactive pile of rubble?

3 destroyers are of far greater utility than 12 subs. And Tomahawk cruise missiles are a far greater deterrent than torpedos and Harpoon AShms. In fact Tomahawks also have far more utility than Torpedos/AShms in terms of Coalition operations.

UGM-109s launched from a submarine are just as effective as air or ship launched variants. But while a large number of nations have the ability to conduct effective anti ship operations, only a comparatively small number are able to conduct anti-submarine operations over a large area. So submarines are likely to be a more survivable and stealthy attack platform.

I also think Canberra class LHD’s are a waste of cash – no defensive systems (bar 4 x 25mm guns) and more critically no intention to operate F-35B. These seem to be purely for support of humanitarian and peace keeping operations.

That gives us a few more frigates as well.

At launch the Canberras will be fitted with the same combat system as the ANZACs, and will have the same 3D radar as the original ANZAC fit. Upgrading them to the same defensive capability as the updated ANZACs shouldn’t be difficult or expensive. As for F-35Bs, time will tell; just look at how quickly the C-17s, M1A1s and FA-18Fs were acquired when government saw the need. After all, a fixed wing aviation capable ship was selected, and the only slightly smaller, rotary-wing only alternative was rejected.