Mohamed Ibrahim Ahmed, who is a citizen of Eritrea, is accused of receiving weapons and explosives training from al-Shabab. The militant group is seeking to further destabilize Somalia's weak transitional government and is considered a terrorist organization by the United States. Ahmed is also charged with providing financial support to al-Shabab.
Ahmed is to appear in federal court again on Tuesday where he is expected to plead not guilty to the charges.
Islamist insurgent groups like al-Shabab control most of Somalia's center and south.