During the 60s, Indonesia tilted to the Russians under Sukarno and with it came massive Soviet assistance. For awhile, they were the top most strategic threat in SEA on the minds of the Australians and pretty much, SEATO.
Massive in the form of:
A dozen Whiskey class submarines

KRI Irian, a Svedlov class cruiser

25 x TU-16 Badgers with AS-1 cruise missiles

Beyond these were the MiGs (13, 21s, later given to the US when they tilted the other way, post Sukarno), PT-76s (still in use, although being retired) and various military aids.