From the beginning, the Germans showed great interest in the high-quality iron ore mines of Ljubija in northwest Bosnia, in the industrial complex (steel, coal and heavy chemicals) in the Sarajevo–Tuzla–Zenica triangle in northeast Bosnia, and in bauxite. As the war advanced and German military involvement in Croatia expanded, more and more Croatian industry was put to work for the Germans. The bauxite mines in Hercegovina, Dalmatia and western Bosnia, were in the Italian zone of occupation, but their total production was earmarked for German needs for the duration of the war under the German-Italian agreement of 1941.