DS9 Season 4 Episode 11 Homefront

Plot

When 27 people are killed at a diplomatic conference being held in Antwerp on Earth, and evidence implicates the Changelings, Captain Sisko travels to Earth to investigate what looks like a bold new offensive by the Dominion that could be a prelude to war. He is accompanied by security officer Odo, a renegade Changeling who opposes the Dominion. Sisko also brings along his son Jake, taking advantage of the opportunity to visit his father, a restaurateur in New Orleans. Due to Sisko's experience dealing with Changelings, Vice-Admiral Leyton puts him in charge of planetary security; together they persuade the President of the Federation to introduce new security measures on Earth, hoping to be prepared if the Changelings attack again. Meanwhile, Jake's friend Nog, a cadet at Starfleet Academy, asks Captain Sisko to help him become a member of the Red Squad, an elite and selective group of cadets.
With the Dominion threat ever looming, paranoia begins to grow, especially after Odo catches a Changeling impersonating Leyton. Even Sisko momentarily suspects his own father of being a Changeling when he is unwilling to submit to a blood test. As matters escalate, all the power on Earth is knocked out, and sabotage is believed to be the cause. Sisko and Leyton decide to prepare Earth for war, and they convince the President to declare a state of emergency on Earth. As the episode ends, Jake and his grandfather witness armed Starfleet security personnel begin patrolling the streets of New Orleans.