Bosco Ntaganda, known as "The Terminator", fled his base in the eastern Democratic Republic of Congo (DRC) after losing control of the most recent rebel group he commanded, the M23, and sought the protection of the Americans.
Embassy officials described their shock at the sudden appearance of the Congolese warlord, who has been wanted by the International Criminal Court at The Hague since an arrest warrant was issued in 2006. US diplomats insisted they had no advance warning of the 39-year-old's arrival, while Rwanda's government denied that he had been hiding in the country prior to his "surrender" on Monday.
The US state department confirmed his presence at its mission and said it was working to facilitate his request to be transferred to a tribunal in The Netherlands. Neither the US nor Rwanda is a signatory to the Rome Treaty that established the International Criminal Court (ICC), but the US is expected to transport him to The Hague regardless.
Western diplomats in the Rwandan capital, Kigali, struggled to explain why a man facing charges ranging from the recruitment of child soldiers to sexual slavery, assassinations and the masterminding of a 2008 massacre in which 150 people were killed, would hand himself in.
"He was a man with few options," said one diplomat. "This was his best way of staying alive."
The former DRC general is believed to have fallen out with his protectors in the Rwandan government as well as rivals in the M23 rebel group. Fighters loyal to Ntaganda have been fleeing across the border from the eastern DRC for the past week since losing a battle with another M23 faction led by Sultani Makenga, a long-time rival of Ntaganda.
Ntaganda's rapid fall from being one of the most powerful military commanders in Central Africa has underlined how quickly alliances can shift in the eastern DRC. He was cited in a UN Group of Experts report to the security council last year as the "highest commander of rebels on the ground" and was alleged to report directly to Rwanda's defence minister. For more than a decade, he has alternated among various armed rebel groups and stints as a general in the Congolese army. Typically, the rebellions ended in peace deals in which the combatants were rewarded with senior posts in the national army. Ntaganda used these positions to amass wealth and recruit militias for fresh rebellions.
The ICC charges relate to two periods: the first from 2002 to 2003, when he was second in command to Thomas Lubanga with the Union of Patriotic Congolese rebel group. Lubanga is the only Congolese soldier so far convicted by the permanent tribunal at the ICC. Despite the 2006 arrest warrant, Ntaganda went on to play leading roles in two more armed groups and was charged with fresh crimes under a separate indictment in 2008. A peace deal between rebels and the government in Kinshasa in 2009 ignored the ICC charges and resulted in him being awarded the rank of general in the Congolese army for a second time.
An ethnic Tutsi, born in Rwanda, Ntaganda grew up in the DRC, but joined the Rwandan Patriotic Front, led by the current president of Rwanda, Paul Kagame, who overthrew the country's Hutu-led government in 1994 after the genocide.
Ntaganda's career has typified the military entrepreneurship that has sustained a war economy in the DRC's Kivu provinces. He used his military power to control the lucrative mineral smuggling networks in Goma, eastern DRC's aid and trading hub, including a sideline in fake gold, according to a UN report.
Ntaganda helped launch a mutiny in the army last year after he became concerned that DRC President Joseph Kabila might hand him over to the ICC. The M23 movement, named after the March date of a past peace deal, recruited other disaffected commanders worried that they might be posted outside the mineral rich Kivu in an overhaul of the army. Despite its lack of clear aims, or popular support, M23 was able to capture Goma from the ineffective Congolese army and UN peacekeepers.
However, accusations that Rwanda was using M23 as a proxy to destabilise its vast neighbour resulted in Western allies withdrawing aid budgets, which then hit the economy. The rebels withdrew from Goma and have since split with Makenga's faction, reportedly willing to agree a peace deal based on folding some of the rebels back into the army. Ntaganda was well aware that he would not have been protected under any new deal.