But even if the trouble had not reached DS9 yet (and considering that the Cardassians were part of the "Peace Talks"), as well as half the Federation under blackout, it is surprising that Starfleet did not raise the alert level across all its territory, as they had no idea where the next attack would occur! It was not just the Aventine attacking Federation subspace antennas, but ships from enemy nations as well (plus Riker had passed onto HQ that the fake Takedown virus would disrupt communications throughout the quadrant, wherever computers were in communication with one another---hence the silent running for Aventine).