While attempting to de-frag an old Cardassian computer system, Jake and O'Brien accidentally activate an automatic security program. As a result, DS9 is instantly locked down, and its self-destruct mechanism is switched on. Unable to reverse this procedure, resident Cardassian Garak tries to convince the computer that he is its original programmer, succeeding only in making things far, far worse. First telecast November 12, 1994, "Civil Defense" was written by Mike Krohn. ~ Hal Erickson, All Movie Guide