A senior commander in the Lord's Resistance Army (LRA) has surrendered to US forces in the Central African Republic (CAR).
Dominic Ongwen is wanted by the International Criminal Court for war crimes and crimes against humanity and is regarded as a deputy commander to LRA head Joseph Kony.
His identity was confirmed by a Ugandan army spokesman.
Earlier, US State Department spokeswoman Jen Psaki said: "If the individual proves to be Ongwen, his defection would represent a historic blow to the LRA's command structure."
The LRA originated in Northern Uganda as a resistance movement among the Acholi people against atrocities committed by Ugandan forces. It is a terrorist militia responsible for the deaths of more than 100,000 people. It is noted for its abduction of thousands of children, whom it indoctrinates by forcing them to kill, mutilate or rape their parents or other relatives, seeking to ensure that they can never return to their former lives. Girls are used as sex slaves. Ongwen has claimed that he himself was abducted as a child.
The Ugandan government has failed to tackle the LRA, which has devastated the northern region. The US provided around 100 special forces troops in 2011 to support African troops seeking senior commanders and offered a $5 million reward for information leadin to Ongwen's arrest.
Ongwen is believed to have commanded the LRA's Sinia Brigade, which has been blamed for some of the worst atrocities the group carried out in northern Uganda.
The group, now thought to number as few as 200 fighters, operated in the Democratic Republic of Congo and South Sudan before moving to the CAR.