FBI sleuths detained a 19-year-old allegedly plotting to detonate a vehicle bomb at an annual Christmas tree lighting ceremony in Portland, Oregon. The arrest was announced late on Friday evening by the Justice Department who stated that Mohamed Osman Mohamud, a naturalized U.S. citizen from Somalia and a student at Oregon State University, was arrested after he attempted to detonate what he believed to be an explosives-laden van.

The vehicle was parked near the tree lighting ceremony in Portland's Pioneer Courthouse Square, a statement from the Justice department said.

The arrest was the culmination of a long-term undercover operation, during which Mohamud had been monitored closely for months as his alleged bomb plot developed. The device was in fact inert, it added.

Arthur Balizan, Special Agent in Charge of the FBI in Oregon, maintained that 'The threat was very real' and investigation showed that Mohamud was absolutely committed to carrying out an attack on a very grand scale.

According to the affidavit filed against Mohamud, in August last year, he was in e-mail contact with an unindicted associate overseas who is believed to be involved in terrorist activities. Later in December Mohamud and his associate reportedly discussed the possibility of Mohamud traveling to Pakistan to engage in violent jihad. Mohamud was supposedly referred to another overseas associate and was provided a name and email address to facilitate the process.

In June this year, an FBI undercover operative contacted Mohamud via e-mail under the guise of being an associate in the operation.

Mohamud and the FBI undercover operative then agreed to meet in Portland in July 2010. At this meeting, Mohamud allegedly told the FBI undercover operative that he had written articles that were published in Jihad Recollections, an online magazine that advocated violent jihad, the police said.

Mohamud also indicated that he wanted to become 'operational.' Asked what he meant by 'operational,' Mohamud stated that he wanted to put an 'explosion' together, but needed help.

Following a second meeting in August 2010, Mohamud allegedly told undercover FBI operatives he had been thinking of committing violent jihad since the age of 15. According to the affidavit, Mohamud then told the undercover FBI operatives that he had identified a potential target for a bomb: the annual Christmas tree lighting ceremony in Portland's Pioneer Courthouse Square on Friday.

Police officials stated that earlier this month Mohamud and the undercover FBI operatives traveled to a remote location in Lincoln County, Ore., where they detonated a bomb concealed in a backpack as a trial run for the upcoming attack. They added that the detainee later recorded a video of himself with the undercover FBI operatives in which he read a written statement that offered a rationale for his bomb attack.

The 19-year-old is expected to make his initial appearance in federal court in Portland on Monday where he could face a maximum statutory sentence of life in prison and a $250,000 fine if convicted.