Right; sounds like this would allow humans to block the AI from improving its resources without having to declare war. Personally, I've disabled Worker stealing, but early attacks on Workers are still a viable tactic (to cripple the opponent), so an AI improvement would be nice to have. The following might work, but would also be quite a bit of work to implement: Spoiler : When a unit on guard (defense or counter AI type), reserve or patrol can reach a threatened Worker in a single turn, that unit moves to protect the Worker; this doesn't really cost the AI anything, so long as (concrete) dangers to cities are given priority. The outer ring is often not reachable in one turn. If the Worker job is not an important one, e.g. not a bonus improvement, pause the job and move to safety. As for bonus resources in the outer ring, change guardBonus so that unimproved bonuses are guarded (pre-emptively). All this only in the early game of course. Edit (six weeks later): It appears that CvUnitAI::AI_defend can guard Workers, and even when there is no hostile unit nearby. That's a BtS function, and not much changed by BBAI/K-Mod. It's only used by units with the reserve or attack AI type, and not with a high priority.