An uninhabited Bajoran moon where the Romulans secretly arm a hospital with weapons, provoking Kira's blockade.
Derna is an uninhabited moon in the Bajoran system. In Image in the Sand, Senator Cretak persuades Kira to have the Bajoran government let the Romulans build a hospital there, but Odo soon learns the facility turns away wounded Starfleet personnel and is heavily armed.
In Shadows and Symbols, Kira blockades Derna with a handful of old Bajoran ships against a far stronger Romulan force. She refuses to back down, and Admiral Ross persuades the Romulans to withdraw.