Summary A cornerstone ceremony in Banja Luka May 7 was to inaugurate the reconstruction of the renowned medieval Ferhadija mosque. But with 3,000 Bosnian Serbs in attendance, Serb nationalists, opposed to the rebuilding of Ferhadija, assaulted ethnic Muslims, set fire to diplomatic vehicles, overwhelmed police and trapped international dignitaries inside for several hours. The riots drew condemnations from the United States, the United Nations, the European Union and the Organization for Security and Cooperation in Europe and raised fears that Serb nationalism in Bosnia is unyielding and that the Bosnian-Serb leadership is to blame. Analysis U.S. and British ambassadors to Bosnia are accusing the Bosnian-Serb leadership of organizing a protest 7 May where top Western diplomats, including U.N. Ambassador Jacques Klein, were trapped in a building by rioting Serb nationalists.