Evil laughter pealed out of the mobile phone. Abshir Ali Mohamed, an al-Shabab defector now wearing a Somali military uniform, had asked his former commander to join him. The commander, an al-Shabab judge known for ordering amputations, said he would instead kill Mohamed.

Somali military and government leaders say Mohamed's defection is an example of a trend growing in their favor, with the East African country's most notorious militant group losing manpower and ground. The 24-year-old former insurgent left al-Shabab less than two weeks ago and now wears a bright blue patch with a white star — the Somali flag — on the shoulder of his government uniform.

"Al-Shabab is no longer. It's going to end soon," Mohamed said last week at freshly dug Ugandan-Somali military base on the outskirts of Mogadishu. The base was set up after African Union troops kicked militants out of the towns of Elasha Biyaha and Afgoye.