Old German friendships, like Croatian nationalists, Slovene servitude, and so on. The WWII buddies -- the Nazi Veteran's Club is kept alive. The Germans never forgave the Serbs for spoiling their dreams in the 20th century.
History is very much alive and present in most of the world. Dismissing history and part of the present is what causes Americans to "misanalyze" these situations consistently. The old Latin saying says Historia est mater studiorum (history is a mother of learning). We are a product of our past experiences, individually and collectively.
That was my first thought. But I thought the Germans were horrified by the Croats after WW2 and had distanced themselves. Perhaps not.