Will Freeciv AI ever use nuclear weapons?

Solution 1:

Yes, AI players in Freeciv can and will use nuclear weapons, however this in turn can cause a nuclear winter so is discouraged. I've only ever seen the AI use nukes on the highest difficulties, and even then rarely.

To disable AI using nukes by editing the ruleset files and removing the Manhattan Project. This should be a section labelled [effect_manhattan_project]. You can also achieve this by editing your save file (it's in plain text) and finding the [player] section and setting the Manhatten Project to destroyed.

If you want to keep nukes and use them more liberally, you should be able to enable/disable nuclear winter by entering /set nuclearwinter disabled (or enabled) into the chat window.