Two Australian warships were closely tracked by the Chinese military last month as they passed some of Beijing's most heavily fortified islands in the South China Sea, as part of a joint show of force with the US and Japanese navies.
Officials with knowledge of the operation say destroyer HMAS Hobart and auxiliary tanker HMAS Stalwart sailed close to the Spratly Islands and were challenged by the People's Liberation Army (PLA) in international waters claimed by China.
