Guess some here are so annoyed of US demanding a lot regarding the possibility of selling their F-35s but I gotta ask, what did you expect? F-35 is one of the 3 only 5th gen jets out there on the field today and the only to be sold to foreign countries. TBH I am quite surprised that - as long as it is true what some members of this forum are saying - it was the US not the Indonesian side who've started the talks about the possible sales of F-35.
Nonetheless you have to know that the US is in the driver's seat in this matter. It's not like they would be selling 100 jets or so or Indonesia could afford so much. I'm not even sure if Indonesia could buy more than 20 of these jets considering its costs. With only that much jet you're not the one who could leverage the negotiation.
Also, every single F-35 operators are required to build F-35 specific infrastructure that meets the US security standards where LM engineers and other US personnel will be stationed to maintain and observe how those F-35s will be operated. They are very distinct and separate from any other air force assets and even those who already operate US jets have to invest on such infrastructure in order to operate any F-35s.
I don't know if Indonesia is willing to have so much US control over their jets tho. That's one of the reason why there are only close US allies who operate F-35s in the first place. Even with all these control and costs that follow - F-35's operating costs are double that of F-15Es - partially due to such strict security standards, the US allies could still see the worth, thus rest assured they are not going to be faced with any US embargo in the foreseeable future. On the other hand Indonesia is seeking more independence in defense.
Also there are no such thing as a "freebie F-16s". It's either in use in the USAF or those ones lying on AMARG or so worn off which is the reason it went there in the first place. 100 freebie F-16s lmao. Also you are delusional if you think Indonesia could "mount pressure" onto the US by using fighter jet program or any other military equipment acquisition as a leverage. You act like if Indonesia is buying 100 + jets like India or something. Remember you guys bought those Hawk trainers with British govn. loan (ECGD loans)? That same govn. loan British govn. never got back from Indonesia. ECGD had to cover it up with British tax money. Same goes with those Korean submarines. 100% funded by Korean govn. loan. European countries and Korea would be willing to do such deals because they want to sell their equipment regardless of the bad terms to establish higher grounds on export markets. You are wrong to expect the same from the US tho. They either do ODA to directly support the country in their military program or do none. On top of that F-35s are only sold as FMS. So no possibility of Indonesia directly negotiating with LM. Also regardless of the administration the congress is quite constant about US's export policy of high tech weaponry so don't expect much change on that matter as well.
Talking about fighter jet acquisition, I'm not so sure if it's at all a good idea for Indonesia to be interested in those Austrian Eurofighters. They are Tranche 1 fighters but even worse off than those Tranche 1 fighters Britain is planning to prematurely retire only after 20 years of operation. No DASS, no Pirate IRST, no AMRAAM, only chaff and flair dispensers. Also it has already been confirmed that Tranche 1 cannot be upgraded into further developed Tranche standards due to internal structural difference. Operating costs lie over 50,000 Euros per hour. That is even higher than F-35. Austrian govn. eventually prosecuted EADS and the program was just a total shit show plagued by lobbying and corruption. What's surprising is that it's the Indonesian govn. who've approached Austria not vice versa. You guys are literally trying to go buy a dumpster pile of trash on your own will.
If Indonesia wants a stop gap fighter until KF-X is finished or wants to quit KF-X altogether and look for replacement, I would suggest it is best to buy more F-16Vs. You guys are already operating those so it makes ton of sense in a lot of ways.
If Indonesia wants an alternative to US manufactured fighter jets go buy the Rafales. Yes it is expensive both in terms of procurement and operating costs but that's what you've gotta pay to escape the US. Gripen is out of contention because the NG variants are almost as expensive as F-16 to procure although cheaper to operate, thus a lot of the key components are either Swedish versions of American/European origin. I'm not sure if this is actually the case tho as seen from the F-35 "negotiation". Also forget F-15EX, it is expensive, thus F-15 is not a jet which US sells to any foreign country. Also they have F-18E/F for that role.
So it's either Rafale, F-16V or F-18E/F.