Diplomatic tensions between China and Australia are set to be reignited after the latter was formally invited to take part in large scale military exercises next month involving the United States, Japan and India.
The Australian Defence Force (ADF) last took part in Exercise Malabar in 2007, before the Australian government withdrew from the naval drills the following year because of concerns over relations with Beijing.
Defence Minister Linda Reynolds has confirmed Australia will participate in Exercise Malabar 2020, which she described as a "milestone activity".
"High-end military exercises like Malabar are key to enhancing Australia's maritime capabilities, building interoperability with our close partners, and demonstrating our collective resolve to support an open and prosperous Indo-Pacific," Senator Reynolds said.
"Exercise Malabar also showcases the deep trust between four major Indo-Pacific democracies and their shared will to work together on common security interests."
Japan and the United States have been pushing diplomatically for Australia's return to the Quadrilateral exercises, which China views as threatening and an effort to contain its military reach.
India had been reluctant to allow the ADF to rejoin the powerful military grouping, but the country's Defence Ministry confirmed a long-anticipated invitation had finally been made.
"As India seeks to increase cooperation with other countries in the maritime security domain and in the light of increased defence cooperation with Australia, Malabar 2020 will see the participation of the Australian Navy," the ministry said.
"The participants of Exercise Malabar 2020 are engaging to enhance safety and security in the maritime domain.
"They collectively support free, open and inclusive Indo-Pacific and remain committed to a rules-based international order."
Decision makes Quad 'very formidable'
Australia is yet to announce which naval assets will deploy to Exercise Malabar in the Indian Ocean, but defence sources have suggested a warship such as HMAS Hobart or HMAS Brisbane would be likely to go.
The Malabar invitation follows a Quad foreign ministers' meeting in Tokyo earlier this month, attended by Foreign Minister Marise Payne.
"It will bolster the ability of India, Australia, Japan and the United States to work together to uphold peace and stability across our region," Senator Payne said.
"This builds on the Comprehensive Strategic Partnership, to which Prime Minister Morrison and Prime Minister Modi agreed on 4 June 2020, and which I progressed with my counterpart, Minister of External Affairs Jaishankar, this month when we met in Tokyo."
India's former Naval spokesman DK Sharma, who has long advocated for Australia's return to the Malabar exercises, said having all four nations taking part made the Quad a more formal security alliance.
"It makes it very, very formidable," DK Sharma told the ABC.
"The way [China] is moving out, the first island chain and the second island chain, now you have Japan on top, you have the Pacific more or less under the control of the US, then we have Australia which will have a good look towards either the Pacific or Indian Ocean Pacific, and then we have India.
"None of us are behaving in a way China is behaving - there is a difference, we are all talking security, prosperity, peace, tranquillity … Those guys are only talking about grabbing the nations, making their ports, militarising them, grabbing the islands."