Hassan said he had fought alongside Arab militants and fighters from Kenya, and that he had seen Omar Hammami, an American al-Shabab leader known as Abu Mansur al-Amriki. Hassan and many of the other teens said al-Shabab treats their youngest soldiers very poorly.
"We don't matter. We're taught how to load and unload a gun. I want a future for myself," Hassan said, explaining why he left.
Al-Shabab is split into about three main factions, the former fighters said. One top leader, often referred to as al-Shabab's No. 2, is Sheik Mukhtar Robow, who is seen by the international community as a more moderate al-Shabab leader, one that aid groups have been able to work with in the past.
A leader like Robow could be a way for aid groups banned from southern Somalia to find a way in to distribute food aid. But one former fighter, 24-year-old Abdullahi Dahir, said aid groups shouldn't trust Robow's word, even if he tells them that they can enter.
The teens seem content at the government-run facility, if not a little bored. There is little for them to do and rehabilitation programs are not yet up to full speed, despite the program being more than six months old.
Government spokesman Abdirahman Omar Osman said that more than 50 al-Shabab fighters have defected and joined government forces since the drought began. He said the government needs more money to cover the needs of the program.
For the former fighters, once they're in, it is their only way forward. Marked men -- or boys, in many cases -- they must stay in government-controlled territory.
"If I walk out of here I'll be killed," said one former fighter who didn't give his name. "Where can I go?"