Asar has cut off diplomatic ties with Ytsur.
Also, as far as knowledge of Greek fire goes, the furthest western state to use or research it was the New Union, and they've been sending people to steal technology from the East (which has been utilizing incendiary weapons for a long time) for centuries.
However, if you just say that you know how multiple technologies work and then say that you just have the hybrid technology from it and even if crude, it is fully capable, and it should not be drawn out of mystery.