Concerned about the impact of piracy on commercial shipping in the Middle East, the United Arab Emirates has sought to take the lead in battling Somali pirates, both overtly and in secret by bankrolling operations like Sterling’s.

American officials have said publicly that they never endorsed the creation of the private army, but it is unclear if Sterling had tacit support from parts of the United States government. For instance, the investigative group reported in July that the counterpiracy force shared some of the same facilities as the Puntland Intelligence Service, a spy organization answering to Puntland’s president, Abdirahman Farole, that has been trained by C.I.A. officers and contractors for more than a decade.

With the South African trainers gone, the African Union has turned to a different security contractor, Bancroft Global Development, based in Washington, to assess whether the pirate hunters in Puntland can be assimilated into the stew of other security forces in Somalia sanctioned both by the United States and the African Union. Among those groups are a 10,000-man Somali national army and troops of Somalia’s National Security Agency, based in Mogadishu, which is closely allied with the C.I.A.

Michael Stock, Bancroft’s president, said a team of his that recently visited the camp where the Puntland force is based witnessed something out of the Wild West: nearly 500 soldiers who had gone weeks without pay wandering the main compound and two other small camps, an armory of weapons amassed over two years at their disposal.

Although the force is far from the 1,000-man elite unit with helicopters and airplanes described in the United Nations report, Mr. Stock and independent analysts said the Puntland soldiers still posed a potential threat to the region if left unchecked.

“Sterling is leaving behind an unpaid but well-armed security force in Puntland,” said Andre Le Sage, a senior research fellow who specializes in Africa at the National Defense University in Washington. “It’s important to find a way to make them part of a regular force or to disarm them and take control of them. If that’s not done, it could make things worse.”