The International Criminal Court says Uganda is obligated to arrest Joseph Kony, leader of the Lord's Resistance Army rebel group.
Thursday's statement from the ICC comes one day after Ugandan President Yoweri Museveni offered protection to Kony if his group stops fighting by the end of July.
The ICC says Uganda's government referred Kony's case to the court, and must honor that commitment.
The court has issued arrest warrants for Kony and other LRA leaders, who face charges of crimes against humanity. LRA rebels are accused of kidnapping thousands of children and using them as fighters or sex slaves.
The group has been fighting in northern Uganda for 20 years. The fighting has forced some 1.6 million Ugandans to abandon their homes.