Ibrahim Suleiman Adnan Adam Harun was captured in 2005 without carrying out the plot targeting U.S. diplomats in Nigeria, prosecutors said. He was extradited to New York City last year and secretly arraigned in federal court in Brooklyn.
An indictment unsealed Wednesday charges Harun with conspiracy, providing material support to al-Qaida and other counts.
An attorney for Harun had no immediate comment. The defendant's next court appearance was set for Friday.
Harun, 43, was born in Saudi Arabia and arrived in Afghanistan shortly before the Sept. 11, 2001, attacks so he could fight with an al-Qaida jihad force against U.S. troops, prosecutors said. After receiving further training from the terror group, he allegedly traveled to Africa with orders to attack the U.S. diplomatic sites.
Authorities said they believe Harun killed American soldiers during his time on the battlefield, where he was known as the "White Rose." They also said the bomb conspiracy had targeted the U.S. embassy in Abuja and a consulate in another Nigerian city, but they provided no further details about the failed plot.
Harun tried to flee to Europe after a co-conspirator's arrest, but he was detained in 2005 in Libya while en route and remained there until June 2011, prosecutors said. After that, Italian authorities arrested him on charges that he assaulted officers on board a refugee ship bound for Italy, and was there until his extradition on the U.S. indictment.
"The defendant was a prototype al-Qaeda operative, trained by al-Qaeda in terrorist tradecraft, deployed to fight American servicemen, and dispatched to commit terrorist attacks throughout the world," U.S. Attorney Loretta Lynch said in statement. "Whether they try to attack our servicemen on the battlefield, or scheme to kill our diplomats and citizens in embassies abroad, terrorists will find no refuge."
Harun faces a possible life sentence if convicted.