Kiwis were involved in research on this 37 years ago , they lacked the financial resources for defending their inshore resources and South Pacific military contractual obligations so looked at using sonar as an asymmetric method to repel invaders, it was hushed up at the time, as indicated how desperate the Kiwis were after loosing goodwill with the USA over its neither confirm nor deny policy on Nuclear weapons .
Quite stupid for the CCP to be practice weaponization of sonar against an ANZAC member as this could have escalated quickly as negative PR if those soldiers had died
