I'm not saying the attacks on the Odyssey, New Bajor, and other Federation ships in the Gamma Quadrant were justified. But you could argue that the Dominion felt the Federation was encroaching on their territory and wanted to send a message to stay the hell away. That didn't stop Alpha Quadrant powers from continuing to explore the Gamma Quadrant, and in some cases, interfering with Dominion planets (i.e trade with the Karrama, Bashir curing the Blight, etc.) War could have been averted if the Feds had stayed on their side of the wormhole.