Serbia has not yet arrested and extradited war-time Bosnian Serb military leader, Ratko Mladic, to the International Criminal Tribunal for the former Yugoslavia (ICTY).
"We call on the authorities in Belgrade to cooperate fully with the tribunal, to include the arrest and transfer of fugitive indictees, particularly Ratko Mladic," State Department spokesman Sean McCormack was quoted by the Associated Press news agency as saying in a statement.
The U.S. will hold back USD 7 million in aid to the government but will continue to provide money for humanitarian and pro-democracy efforts, the AP added.
McCormack said Washington would be willing to reconsider its decision should Serbia show it was cooperating with the tribunal.