Brendan Nicholson – John Sanderson well remembers trudging through the jungle in northern Cambodia in 1993 with a young Indonesian battalion commander trying to find feared Khmer Rouge fighters.
At the time, Lieutenant General Sanderson was the Australian officer in command of 16,000 peacekeepers from 34 countries sent to rescue Cambodia from the carnage of the Pol Pot years as the military component of the UN Transitional Authority in Cambodia.
The then Lieutenant Colonel Ryamizard Ryacudu commanded an Indonesian battalion that was a key part of that force.
They were tough and dangerous times long remembered by both officers. The shared experience was also crucial to the establishment of a network of professional relationships which have, in times of tension, provided Australia with effective channels into regional capitals as geographically diverse as Jakarta and Beijing.
Sanderson went on to become chief of the Australian Army and later governor of Western Australia and Ryamizard rose to the rank of general and became Indonesia's Defence Minister.
When Ryamizard and his colleague, Indonesian Foreign Minister Retno Marsudi, came to Sydney for talks with their Australian counterparts, Marise Payne and Julie Bishop just before Christmas, the Indonesia Defence Minister said he wanted to catch up with the retired Sanderson and another former army commander, retired Lieutenant General Peter Leahy.
They had dinner in Sydney and discussed at length Cambodia and the current relationship between their two nations. Payne noted the importance in international relations of what she called the people-to-people links – close friendships that grew out of professional relationships.
The three men are part of a largely below-the-radar process of military diplomacy.
Members of alumni groups made up mainly of former military and police personnel and diplomats who have kept in close contact since working or studying together as young officers have provided a highly effective back channel to keep open communications between Canberra and Jakarta at times of tension between the two governments.
That was the case during the row over claims that an Australian spy agency had monitored the phone calls of senior Indonesians including then president Susilo Bambang Yudhoyono and his wife, tensions over asylum-seeker policies and anger over the executions of Australian drug smugglers Andrew Chan and Myuran Sukumaran.
At one point, the now Professor Leahy was chosen by Tony Abbott to carry a letter to the Indonesian government. It's part of a very effective exercise in military diplomacy that runs separate to but in parallel with more formal links between intelligence agencies.
The Australian reported a year ago that despite tensions between Jakarta and Canberra, a decision had been made that Australia would inform Indonesia immediately if its intelligence agencies uncovered evidence of terrorist threats in that country. Tensions at the top would not interfere when lives were at stake.
Australian agencies have provided crucial intelligence to their Indonesian counterparts since the 2002 Bali bombings that killed 202 people, including 88 Australians. That information has led to the arrests of significant numbers of terrorist suspects.
Much of that intelligence has come from comprehensive surveillance carried out for decades by the Australian Signals Directorate, formerly the Defence Signals Directorate, over a vast part of the region using a network of bases shared with the US and from the "Five Eyes" intelligence-sharing network involving the US, Britain, Australia, New Zealand and Canada.
Indonesian officials have told Australian counterparts that given the heightened security tensions in the region, they were keen to become a "sixth pair of eyes".
A key alumni group is Ikahan Alumni Pertahanan Indonesia-Australia, which has many hundreds of members. Close and confidential contact is maintained by a "senior advisory group" of former generals and their equivalents in the two nations' navies and air forces.
Members of the group meet regularly in Australia and Indonesia to talk on matters of mutual concern. They can pass on messages to Australian Defence Force chief Mark Binskin or his equivalent, the Panglima, commanding general of the Indonesian armed forces, the TNI.
This process has created throughout the region and far beyond it links that can be crucial in providing help quickly in an emergency or defusing a crisis.
In March 2011, when Japan was devastated by a tsunami that killed thousands and devastated a huge area that included the Fukushima nuclear power plant, the then Air Marshal Binskin sent a text to his counterpart there asking if the ADF could help.
Over many years, Binskin had built up a strong personal contact with Shigeru Iwasaki, who now heads the Japan Self Defence Forces. General Iwasaki had replied that help would indeed be appreciated, and two RAAF C-17 transport aircraft were dispatched. They flew in a search-and-rescue team, and rushed a water cannon to Fukushima to help cool reactors.