However, by the late 1980s the Soviet Union was collapsing and replacement of the again subsiding DYE stations was deemed not worth the expense. In connection with the turn-over of Sondrestrom to the Danish government in 1992, the DYE stations were abandoned and left to sink into the ice, an ongoing process. DYE 1-3 were evacuated in 1988, and DYE 4 in September 1991. In addition to air defense radar tracks, Dye Stations provided thirty years of meteorological observations—the 2 ice cap sites (e.g., Dye 3) were used for ice core drilling.