Khekarians were a warring civilization. They had a long history of raids and assaults against the Chiddran. In the last hundred years, their aggression had intensified and the gloves were off for real.
Not only were the Khekarians the instigators of a full-blown galactic war against the Chiddran Empire, they also claimed galactic dominance.
They already had most of it, now they wanted it all.
Terrans were the new kids on the block, their whole Sector a poor cousin to the affluent Chiddran Reach. The fear they felt was simple. When the Khekarian Empire finished with the Chiddran one, how long would it be before their attention turned to the young and still pitifully weak Terran expansion?