An attempt in 2373 by a Changeling posing as Julian Bashir to explode Bajor's sun and destroy the Federation, Klingon and Romulan fleets gathered at Deep Space 9.
The Changeling plot to destroy the Bajoran sun is the climax of the Deep Space Nine episode By Inferno's Light. A Dominion fleet comes through the wormhole but turns towards Cardassia, where Gul Dukat announces that his people have joined the Dominion. Expecting an attack, Benjamin Sisko gathers Starfleet and Klingon ships at the station, and Romulan warbirds unexpectedly arrive to help.
That gathering is what the Dominion wants. The false Bashir sabotaged the attempt to seal the wormhole, and he now flies the runabout Yukon towards the sun with a bomb of trilithium, tekasite and protomatter that would cause a supernova and destroy Bajor, the station and all three fleets.
A message from the real Bashir, just escaped from a Dominion prison, exposes the plan. Kira Nerys and Jadzia Dax chase the runabout in the Defiant and destroy it with a few seconds left.