The True Way was a Cardassian terrorist organization that operated in the 2370s. They believed the Federation to be the greatest threat to the Cardassian people, and the cause of the Cardassian Union's economic and political difficulties. Until the 2370s they had never commited any acts of terrorism against the Federation or Bajor.
In 2372, they detonated a bomb that destroyed the runabout USS Orinoco, which was carrying the senior officers of Deep Space 9. (DS9: "Our Man Bashir")
Later that year, members of the True Way unsuccessfully attempted to assassinate Bajoran First Minister Shakaar Edon on Deep Space 9. (DS9: "Crossfire")
Apocrypha
The True Way reemerges in 2376. (DS9 Pocket: Worlds of Star Trek: Deep Space Nine, Volume 1)