Newly appointed Defence Minister Christopher Pyne has declared that maintaining Australia's regional "capability edge" and ensuring the South China Sea remains open and free are key priorities as he confronts an uncertain strategic environment dominated by Beijing's increasing assertiveness and a global order disrupted by US President Donald Trump.

A stark demonstration of Chinese assertiveness came just this week, when a Chinese warship nearly collided with a US destroyer conducting a freedom of navigation patrol in the disputed Spratly Islands. US officials accused the Chinese of sailing in an "unsafe and unprofessional" manner, while Beijing charged that the US had violated its sovereignty.