An article written some 6 years ago about the Koral development is making some interesting claims.
According to this article, Turkey, in around 2012-13 bought a S300 system from Belarus (sans missiles) and investigated the innards of the system and came up with the Koral to counteract the S300.
It is also stated that the article has since been upvoted by an Aselsan ex-employee. (His credentials check out)
Answer (1 of 5): S-400, Pantsir and EW/ECM equipment on Su-30/Su-34 was made to be able to resist the best of USA's electronic warfare platforms, color me sceptical when I doubt Turkey's know-how when it comes to making anything capable of compromising it. If by some miracle the Turks have made s...
www.quora.com
If this is correct and Redet and Koral-2 is also being produced with what we have learnt from s400 to counteract Russian systems , it is very intriguing.