A Danube-class runabout assigned to Deep Space 9, stolen in 2373 by the changeling impersonating Julian Bashir in an attempt to blow up the Bajoran sun.
The USS Yukon was one of the runabouts stationed at Deep Space 9, named like the others after a river of Earth.
In By Inferno's Light, the Founder who had replaced Doctor Bashir for weeks takes the Yukon while the combined Federation, Klingon and Romulan fleet waits near the station for a Dominion attack that never comes. The runabout carries a device built from trilithium, tekasite and protomatter. Detonated inside the Bajoran sun, it would set off a supernova that destroyed the station, Bajor and the fleet together.
A message from the real Bashir, escaping from Internment Camp 371, exposes the plot. Kira Nerys takes the Defiant after the Yukon and destroys it before it reaches the star.