Prime Minister Anthony Albanese has said the signing of a landmark bilateral security pact shows Australia's relationship with Indonesia is "stronger than ever".
Albanese and Indonesian President Prabowo Subianto ratified the treaty during a signing ceremony in Jakarta on Friday, elevating defence ties between the two countries.
Under the Treaty of Jakarta, both nations would consider a military response if either came under attack.
Albanese said the treaty cemented ties between Australia and Indonesia.
"Australia and Indonesia's relationship is stronger than it has ever been," he told reporters in Jakarta.
"The treaty is a significant extension of our existing security and defence cooperation. It demonstrates the strength of our partnership and depth of our trust and cooperation.
"We are more than just partners. We are close friends."
The agreement means Australia and Indonesia will hold talks at a leader and ministerial level on a regular basis.
The treaty was first unveiled in November during a visit by Prabowo to Australia.
The agreement would help boost security in the region, the Indonesian president said.
"This treaty reflects the commitment of both countries to continue strengthening cooperation, to maintain their respective security, as well as to contribute concretely to the peace and stability in the Indo-Pacific region," he said.
"Indonesia and Australia are destined to live side by side and we have chosen to establish that relationship founded on mutual trust and goodwill."
As part of the treaty, senior Indonesian officials will be able to be embedded in the Australian Defence Force.
Foreign Minister Penny Wong, who is joining Albanese on the trip, said the agreement was the most important strengthening of the partnership in 30 years.
"In these uncertain times, this is a demonstration of the importance we place on our relationship and the respect we have for each other," she said.
A memorandum of understanding was also signed between Australia and Indonesia's sovereign wealth funds to boost two-way investment.
Albanese's trip to Indonesia is his fifth as prime minister and second since his re-election in 2025, when he opted to make Indonesia the first country he visited after retaining office.
Non-alignment and democratic backsliding
Australian Strategic Policy Institute senior analyst Gatra Priyandita said the agreement could be seen as a positive step in the context of the broader bilateral relationship, but highlighted that the agreement didn't include any concrete security commitments.
"There is going to be no element concerning mutual commitment to each other's security," he said.
Indonesia has long upheld a foreign policy of non-alignment to avoid being entangled in conflicts, and Priyandita said Indonesia remained "very allergic" to the idea of defence alliances to preserve its non-alignment policy.
Prabowo has faced domestic criticism over the perceived deviation from that norm.
The Indonesian president's political record was also highlighted by Melbourne University's Tim Lindsey, a leading expert on Indonesian law, who warned greater ties with Australia's "northern shield" wouldn't make the relationship easier for Canberra.
"Indonesia's slide away from liberal democracy and towards authoritarianism presents new challenges for an Australian government which must interact with Indonesia," Lindsey told AAP.
A draft law put forward by the Indonesian government against disinformation and foreign propaganda could lead to a crackdown on civil society groups.
This could lead to a scenario where Indonesians in Australia are targeted, Lindsey said.
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