The United States expressed disappointment Friday over an admission that military officers of Serbia and Montenegro had given shelter in past years to indicted Balkans war crimes figure Ratko Mladic. The former Bosnian-Serb military chief is wanted by the Hague tribunal on genocide charges.

The United States is making clear its unhappiness over the revelation about Ratko Mladic, and warning again that aid to Serbia-Montenegro, and its future links to NATO, depend on the apprehension of Balkans war criminals.

The U.S. comments follow a report Wednesday by Serbia-Montenegro's main defense body, the Supreme Defense council, that Mladic had undeniably been given shelter until 2002 at various Serbian military sites.

Mladic, the former Bosnian-Serb military chief, is wanted by the International Criminal Tribunal for the former Yugoslavia, the I.C.T.Y., on various charges, including genocide for the massacre of eight-thousand Muslim men and boys at Srebrenica in 1995.

Wednesday's report said Serbian authorities have since been unable to locate Mladic. But State Department Spokesman Sean McCormack said it was a long overdue admission that he had gotten support from Serbia-Montenegro military personnel. "The support for Ratko Mladic has occurred even though the authorities in Serbia and Montenegro were well-aware of their international obligations to apprehend and transfer fugitive indictees to the I.C.T.Y. It detracts from Serbia and Montenegro's aspirations for Euro-Atlantic integration. We are disappointed that despite many statements of intent from the government of Serbia and Montenegro, progress has not been made on the apprehension of Mladic," he said.

Mladic and former Bosnian-Serb president Radovan Karadzic are the most prominent Balkans war crimes figures still at large.

Like Mladic, Karadzic is also reported to have been hidden by supporters in Serbia and in the Serb entity in Bosnia-Herzegovina, the Republika Srpska.

Spokesman McCormack said the latest disclosure must lead to long-overdue, concrete action by Belgrade authorities to intensify efforts to apprehend Mladic, Karadzic and other fugitives and deliver them to the Hague.

The Bush administration has made clear that Serbia-Montenegro's chances of joining NATO's Partnership for Peace are nil as long as Mladic and Karadzic remain at large.

Spokesman McCormack also said U.S. aid decisions for that country will be based on actions, not words, concerning war crimes suspects.

The United States committed $100 million in post-war economic aid to Belgrade in 2001, but some of it still has not been delivered because of the war crimes issue.