Washington will resume aid to Serbia amid hopes that war crimes suspect Ratko Mladic will soon be in custody, a US State Department official has said.
Undersecretary of State Nicholas Burns said the former Bosnian Serb military chief's days in freedom were numbered.
Gen Mladic is wanted on charges of genocide over the deaths of more than 7,000 Muslims at Srebrenica in 1995.
The US froze economic aid to Serbia because of its apparent failure to co-operate with The Hague tribunal.
"My strong impression from my discussions here in Belgrade is that the [Serbian] government is working very seriously to find General Mladic and there will be a sincere attempt to capture him or to have him voluntarily surrender and to send him to the Hague," Mr Burns told reporters.
"We are confident that his days in relative freedom are numbered."
He said Washington would now release $10m (£5.4m) in aid.
The Serbian government has denied a press report that it has been negotiating to secure Gen Mladic's surrender within 10 days.
Belgrade has come under increased pressure from the international community to capture Gen Mladic and wartime Bosnian Serb political leader Radovan Karadzic.
The public screening last week of a video apparently showing the execution of Muslim civilians at the hands of Serbian paramilitaries in 1995 shocked many Serbs.
UN chief war crimes prosecutor Carla del Ponte has said her office had more video evidence on the massacre of Bosnian Muslims in Srebrenica.
Ms del Ponte said she needed "Karadzic and Mladic in The Hague before 11 July" as a way of paying tribute to those who lost fathers, sons and husbands in the massacre.
Serbia and Montenegro have surrendered more than a dozen war crimes suspects in the past six months.