Stargate Atlantis: Season 3, Episode 20

3 - 20: First Strike

With the arrival of the Apollo to Atlantis comes intel that the Replicators appear to be building a large armada to directly attack earth. Planning to strike first, Col. Ellis with the aid of the Atlantis team launches a surgical strike nuking the entire armada. Believing that all imminent danger has been avoided the team is shocked when a satellite housing a stargate takes up geosynchronous orbit above Atlantis.