FYI, South Korea is already developing its indigenous 10k lb engine with the help of Doosan Enerbility, a company that has successfully developed 380MW gas turbine with a TIT of 1,680°C(higher than 1,649 °C of F119) recently.
https://www.doosan.com/en/media-center/press-release_view?id=20172690
https://www.doosanenerbility.com/en/about/news_board_view?id=21000611
>Doosan’s foray into the aircraft engine business has already started. The company is currently participating in the “10,000 lbf* gas turbine engine development for unmanned aerial vehicles,” a project led by the Agency for Defense Development. The project consists of a total of three initiatives, with Doosan Enerbility taking on two of the initiatives deemed as being the most challenging and involving key technologies. Doosan will be leading the “engine layout design and components analysis” and the “casting & forging of turbine vanes/blades and post-processing” initiatives, with the aim to complete the basic design by 2027. Doosan is also working on the conceptual design of an advanced aircraft engine**, a work that was commissioned by the Korean government in an effort to secure Korea’s own fighter jet engine technology.
Once this engine is ready, they're using it as a base for 16k lb engine that's meant to be mounted on KF-21. Rolls Royce is just uppity because Koreans are advancing at a record pace.