On 15 September 2021，Australia，the United Kingdom and the United States announced Australia-UK-US Security Partnership（AUKUS）. AUKUS’s first major plan is that the United States and the United kingdom jointly provide nuclear submarine technology to Australia. This cooperation is upsetting the regional strategic balance in both Southeast Asia and Western Pacific，raising risks of nuclear proliferation throughout the Asia-Pacific region and even the world. Australia played an extremely important and special role in the establishment of AUKUS. Australia made significant adjustments to its national defense strategy in 2020，with a particular focus on armament expansion. AUKUS provided an oppor-tunity for Australia’s national defense strategy adjustments，and Australia has become the only regional security increment since the establishment of AUKUS. Because Australia views the periphery as a direct strategic interest zone and tries to cover the periphery with military projection capabilities，it is bound to influence the regional security order where Southeast Asia countries and Pacific Island countries are located.