German Secretary of State for European Affairs Anna Lührmann was expelled from the Serb entity of Bosnia in retaliation for German sanctions against the Bosnian Serb leadership.Bosnian Serb police on Friday expelled a top German foreign ministry official from Republika Srpska (RS), Bosnia and Herzegovina's ethnic Serb entity, after she met with opposition groups. German Secretary of State for European Affairs Anna Lührmann said representatives of RS leader, Milorad Dodik, threatened her with "violence" in the entity's capital city, Banja Luka. In a post on social media, Lührmann wrote that Dodik had "demonstrated again his destructive behaviour." "His representatives threatened me and my delegation with violence," she added. Lührmann had to cancel her Friday meetings and left Banja Luka under police escort, according to the Bosnian national television. Why was Lührmann expelled? Bosnian Serb authorities declared Lührmann "persona non grata" as part of what they said were "reciprocal measures" following sanctions by Germany. "I expect the police to escort her out of Republika Srpska very quickly and for good," Dodik wrote on social media. Germany and Austria on Thursday banned Bosnian Serb leader and his two closest aides from their territory, accusing Dodik of threatening the security of Bosnia and the region. Dodik has triggered a constitutional crisis by defying rulings by the international envoy tasked with preventing the multiethnic Balkan state from sliding back into conflict. This has escalated into a legal and political standoff pitting Dodik and his allies, Russia and Serbia, against the United States and the European Union. A divided state in the Balkans Since the end of an inter-ethnic war in the 1990s, Bosnia and Herzegovina has been divided into semi-autonomous halves: the Serb-majority Republika Srpska and the Bosnian and Croatian-led Federation of Bosnia and Herzegovina. Each has its own government and parliament, with only weak central institutions holding the country of 3.5 million people together. For years, Dodik has led a campaign to chip away at Bosnia's weak central institutions, threatening the Serb entity with secession. Edited by: Zac Crellin