Delkar VII was a small planetoid on the edge of the Cardassian/Federation border. It was rich with minerals rare to the Cardassian culture. When negotiations re-aligned the border between the Federation and Cardassian space, the Cardassians expressed interest in the planet for mining purposes. When the Federation's use of the planet as an observation post came to an end around the year 2371, Benjamin Sisko was authorized to use it to bargain for the release of Thomas Riker when dealing with the High Council of Cardassia Prime, an offer the Council turned down. (DS9 - Sole Asylum comic: )