One thing about a SOSUS array is that it depends upon arrays of hydrophones linked by cables. Unfortunately today hostile powers can interfere with the cables and play silly buggers, drastically reducing their effectiveness.I think there is something in the Australian document about investing billions in an undersea sensor network. Apart from the potentially prohiberative cost, this is something i would like to see in NZ and perhaps we could piggyback onto the Aust program- at least across our northern approaches.
I agree that the maritime domain presents the greatest threat to NZ, but the threat matrix is not just limited to surface and sub surface vessels, it also includes aircraft that can be the launch platforms for AShM and the PLAAF & PLAN H-6D is a very long legged aircraft.In my mind and direct threat to NZ or NZ trade will be maritime -surface or subsuface. (or cyber- but thats another conversation). Beefing up ASuW/ASW capability would therefore be my priority (NZ ANZAC and P8 launched LRASM/JSM deterrence).
There's no pussy footing around the issue, but the PRC is the main threat to stability and peace in the Asia Pacific region and the geostrategic strategic situation is deteriorating, not improving. Scott Morrison is correct when he compared the current situation to that of the 1930s and the evidence suggests that it's going to get worse. Some say that you can't compare the PRC to Nazi Germany, but there are similarities. Opportunistic land grabs, in the PRC case building illegal reclamation structures in the SCS; the persecution of Uighurs because of their race and religion; bullying of neighbouring countries and others; the disregard and ignoring of international treaties and laws.
In the 1930s NZ buried its own head in the sand until it was almost to late. This time we cannot afford to do the same because we won't get the same warning period and we won't be able to rearm like we were able to in WW2, because the US is not in a position to manufacture arms like it did then. It doesn't have the industrial capability, plus weapons and platforms are far more complicated today.