Mr in this world you never know even Russia was not hostile to Ukraine two years ago all of a sudden it attacked them Indonesia can have really high tensions with China and Australia any time and also few other countries they are in really volatile region so better if they are prepared
To be honest with you, even in their current defense situation, Indonesia already has the largest armed forces in ASEAN. There is no country that she can't 'squash' if ever conflict wast to break out (not that it would happen, because it won't). Indonesia was the founding member of SEATO, and the founding member of ASEAN. This political maturity and ingenuity on Jakarta's part to foster a united Southeast Asian community has ever been part of their strategy. In fact it was this very basis that was cataylzed in Indonesia + Philippines visage to prevent communism from expanding -- that SEATO was created. ASEAN took after SEATO, but emphasized economic, political and cultural intercommensurability processes.
Indonesia was the country that called for peace between 2010-2011 Thailand-Cambodian border war. It was Indonesia that called for community and cooperation in the ASEAN Foreign Ministers' meeting in 2012-2013 and has been the active member in reminding members to observe the 2002 Code of Conduct in the SCS.
She is as much vested in peace. She has 'rivalry' with Malaysia and to an extent Singapore, but it is friendly camaraderie, never militant hostility. The region is too intertwined now for war.