While in the Great Link ("Broken Link"), Odo suspected that the Changelings were hiding information from him. What he was able to gleen from the Link allowed him to realize that Klingon Chancellor Gowron is actually a Changeling. Starfleet requests that Sisko reveal Gowron for who he truly is and put an end to the hostile actions of the Klingon Empire.
When the Cardassian occupation of Bajor ended in 2369, the mining space station Terok Nor was left abandoned, its systems ripped out. By invitation of the Bajoran provisional government, Starfleet stepped in to oversee the rebuilding and day-to-day operations of the newly christened Deep Space Nine.
The years of Starfleet's nonintervention into Cardassian matters, however, had taken its toll on relations with the Bajorans. Consequently, Starfleet's position was a tenuous one; many Bajorans, suspicious and hostile as a result of decades of Cardassian oppression and brutality, did not greet the Federation's presence with open arms. The Federation's assistance is put to the test as DS9 becomes a center of travel and commerce that stretches into the Gamma Quadrant.