Serbia's authorities have tightened the noose around top war crimes suspect Ratko Mladic in an attempt to avoid international sanctions. If the wartime Bosnian Serb army commander, charged with genocide by the UN war crimes tribunal, is not surrendered to the court by month's end, Serbia could face political and economic isolation similar to that during the reign of Slobodan Milosevic in the 1990s, Serbian officials warned. But Mladic, who has been on the run since his 1995 indictment, remains highly popular at home. Prime Minister Vojislav Kostunica, whose government is shaky and depends on the support of nationalists, seemed hesitant to forcefully arrest him. "This time I believe they'll arrest him because they are being pushed against the wall," said Natasa Kandic, Serbia's leading human rights activist.