The FBI said Omer Abdi Mohamed, 26, admitted to having a role in a plan to recruit Somali men to travel to the country and fight against Ethiopian forces.
Mohamed in his plea admitted to meeting in various places throughout Minneapolis in late 2007 to recruit men for operations in Somalia. The FBI said he helped coordinate "a secret plan" that including Somali men living in Minneapolis traveling to Somalia.
FBI officials said some of the families of the men who went to Somalia only learned about the fate of their relatives through Internet videos used as propaganda by al-Shabaab, al-Qaida's affiliate in Somalia.
The FBI in June said fingerprint evidence from a May suicide attack that killed two peacekeepers in Somalia identified one of the bombers as Farah Mohamed Beledi. He was indicted last year by a grand jury in Minneapolis on terrorism offenses. He was one of 13 men charged with terrorism after traveling to Somalia to join al-Shabaab.
Mohamed faces a maximum penalty of 15 years in prison and a lifetime of supervised release, the FBI said. His indictment is part of Operation Rhino, an investigation into Somali men from Minneapolis recruited to fight with al-Shabaab.