Season 5 Episode 9 - Between Two Fires

At the funeral of Omoc of the Tollan (from "Enigma"), High Chancellor Travell approaches the team and opens discussion about trading high technology. The Tollan Curia want resources in return for ion cannons. Meanwhile, Narim warns Sam that the Tollan have some ulterior motive, and Omoc may have been murdered to insure his silence. Jack and Teal'c track the shipment and discover it will be used to make bombs that utilize the Tollan's phase-shift technology to phase through Earth's Stargate iris. Daniel and Sam are captured, and discover that a mysterious unnamed System Lord has developed pyramid ship shielding immune to the Tollan's ion cannons. The Lord's representative, the believed-to-be-deceased Tanith, forces the Tollan to test a bomb and destroy Earth, since if the Gou'ald do so it will break the treaty with the Asgard. With the aid of Narim, Jack and Teal'c destroy the bombs, and the Gou'ald go to war with the Tollan.