The United States has sent 100 special forces soldiers to the Central African Republic to help co-ordinate the fight against the Lords' Resistance Army led by Joseph Kony.
The LRA is accused of rape, mutilation, murder and the recruitment of child soldiers.
Kony and his aides have been wanted by the International Criminal Court in The Hague since 2005.
The LRA was chased out of Uganda in 2006. The Ugandan army pursued him, but failed to catch him, despite getting close on a number of occasions.
The US forces are not hunting Kony themselves, but are assisting those doing so. They are also collecting intelligence on him.
The BBC reports people still live in fear of Kony in Gulu, northern Uganda, even though the area has seen no LRA activity for more than five years.
According to former LRA fighters, the organisation now has around 300 members, down from a peak of 2000.