 During her deployment in North Norway she patrolled Norwegian territorial waters and repeatedly had to sink Soviet naval mines that had broken their moorings and drifted into Norwegian waters.During the Winter War all three of the "Sleipner"-class destroyers commissioned at the time (, "Gyller" and ) were deployed to different ports in Finnmark, with "Gyller" based in Kirkenes.One occasion when "Gyller" had to dispose of a mine was on 22 March 1940 when a Royal Norwegian Navy Air Service M.F.11 seaplane operating from an improvised base at Vadsø spotted a mine drifting in the Varangerfjord and directed the destroyer to the scene.