The Borg are back.
But what are they after? Their modus operandi appears to have changed. It appears they have caused little destruction so far and not assimilated anyone and their only victim so far appears to be a young ensign unfortunate enough of being the redshirt.
This is going to be tough of Sisko considering his history with the Borg, not to mention a hell of a challenge for an, as of yet, untested starship captain.