The Kabrel system was an uninhabited binary star system with two planets, located in Federation space near the Cardassian border. The binary stars in the system generate a great deal of ionic interference, discouraging settlement.
In 2374, the Dominion surreptitiously attempted to acquire the Kabrel system in the re-drawn border they proposed to the Federation during the short-lived peace talks following Operation Return. Their purpose was to gain control of Kabrel I, which represented a potentially unlimited source of ketracel-white. Doctor Julian Bashir and four other genetically engineered Humans advised the Federation to cede the Kabrel system to the Dominion, to forestall an immediate full-scale offensive. (DS9: "Statistical Probabilities")