The most hopeful sign of progress so far, says Graff, is an agreement between Milosevic and Croatian president Franjo Tudjman to resolve their territorial differences in Eastern Slavonia, and to return refugees. "It's certainly good that they addressed that, since only a few days ago Tudjman said he would take the city of Vukovar, in the disputed area, by force." Despite such progress, however, Secretary of State Warren Christopher has said that "vast differences [remain] to be bridged." Christopher has insisted on dealing with human rights questions, including the massacres of Muslims by Bosnian Serbs. He has also made it clear that no U.S. troops would be sent to the area if Bosnian Serb leaders Radovan Karadzic and General Ratko Mladic -- now under indictment by the international war crimes tribunal -- are still in power.