Mohamed Osman Mohamud was sentenced to 30 years in prison.

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NEW: Mohamed Osman Mohamud, a naturalized citizen, gets 30 years in bomb plot

Feds say he planned to bomb a 2010 Christmas ceremony in Portland, Oregon

Mohamud said he wanted people to leave "dead or injured," an affidavit says

He exchanged emails with al Qaeda member and another terrorist suspect

CNN  — 

A 21-year-old naturalized U.S. citizen from Somalia was sentenced Wednesday to 30 years in prison for plotting to bomb a 2010 Christmas-tree lighting ceremony in Portland, Oregon.

Mohamed Osman Mohamud was convicted after a two-week trial last year on one count of attempting to use a weapon of mass destruction, namely explosives.

Mohamud was a 19-year-old Oregon State University student when he was arrested on November 26, 2010, and accused of trying to blow up what he believed to be an explosives-laden van parked near a holiday event in Pioneer Courthouse Square, authorities said.

The bomb was actually a fake planted by federal agents involved in the extensive undercover operation. Mohamud described the device as “beautiful,” according to his arrest affidavit.

Born in Mogadishu in 1991, Mohamud moved to the United States and became a naturalized U.S. citizen, settling in the northwestern Oregon city of Corvallis. Years before he enrolled at Oregon State University, he’d started thinking of taking part in a violent jihad, according to the U.S. Justice Department.

In February 2009, he began exchanging the first of about 150 emails with Samir Khan, a now-deceased al Qaeda member who published two online publications tied to the terrorist group, Jihad Recollections and Inspire. According to the Justice Department, Mohamud wrote several articles under assumed names for the former publication.

The Oregon resident began communicating electronically in August 2009 with another accused terrorist, Amro Al-Ali, who is now being held in his native Saudi Arabia on terrorist charges, federal authorities said.

The two discussed Mohamud’s possible travel first to Yemen and then to Pakistan’s Northwest Frontier province for terrorist training.

“Yes that would be wonderful, just tell me what I need to do,” Mohamud wrote back in December 2009, the affidavit stated.

That trip never happened, despite Mohamud’s efforts to contact intermediaries to facilitate it. But he was reached in summer 2010 by a man who, unbeknownst to him, was an undercover FBI employee.

The FBI investigation moved to another level, including several discussions and trips involving Mohamud and undercover agents.

On November 4, 2010, on the way back from a trial run to a remote location to detonate a bomb, he was asked what he hoped would happen to those attending the Portland holiday ceremony, a family event that includes people of all ages.

“I want whoever is attending that event to leave … either dead or injured,” Mohamud said, the affidavit states.

Having canvassed to the area to find a spot to inflict the most casualties, Mohamud got what he believed to be a live bomb from the undercover agents. But the device was inert, and after his second attempt to detonate it, Mohamud was arrested.

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CNN’s Amanda Watts and Greg Botelho contributed to this report.