Sydney, March 3 -- An unprecedented move by Chinese warships to "circumnavigate" Australian territory has touched a nerve, as the country grows increasingly concerned about China's reach and intentions in the region.

Australia's military spotted three Chinese warships on Feb 10 in the Arafura Sea, off the northern tip of Australia.

But Canberra appeared to have little inkling that the ships were just setting out on an unprecedented voyage that would bring them within 150 nautical miles of Sydney, as part of what is likely to be - according to Defence Minister Richard Marles - a complete circumnavigation of Australia.

The ships first made national and international headlines on Feb 21 when it was revealed that almost 50 commercial fligh...