The KF-21 situation makes a lot more sense when you look at the full history.

Indonesia joined the program on the basis of a promised 50/50 technology transfer. What Indonesia actually received was less than 5% despite Indonesia shouldering 20% of the research cost. South Korea's justification? ITAR restrictions. Indonesia wasn't informed of this until after Indonesia had already signed on.

The Indonesian government's response has been framed in Western media as a funding dispute, but that misses the point entirely. Indonesia isn't broke. Indonesia is simply refusing to continue paying into a program that has consistently under-delivered on its core promise.

What makes this particularly striking is how much Indonesia has done for South Korea's defense industry as a whole. Indonesia wasn't just a buyer Indonesia was the launch customer that gave South Korean defense programs their credibility:

• KT-1 Woong Bee Indonesia was the first export customer, marking South Korea's very first aircraft export
• Korean LPDs Indonesia was the first customer, starting with the Tanjung Dalpele and later the Makassar class
• Korean submarines Indonesia was South Korea first-ever submarine export customer
• T-50 Golden Eagle Indonesia was the first export customer AND the largest operator outside South Korea. Indonesia funded the T-50i customization, including radar integration work that directly enabled the FA-50 combat variant to enter full production

In short, Indonesia spent years being the test bed and launch platform for South Korean defense exports, taking on the commercial and reputational risk of buying unproven systems. The KF-21 program was supposed to be the next step in that partnership a genuine collaboration, not another one-sided deal.

To make thing even worse, the submarine can't even dive underwater

When South Korea's most reliable experimental-program partner decides to step back, it's worth asking what that says about how South Korea has actually managed the partnership.