US authorities thwarted a plot to blow up a car bomb at a Christmas tree lighting ceremony in the western state of Oregon and arrested the suspected Somali-US bomber, officials said Saturday.
The Justice Department identified the chief suspect as 19-year-old Mohamed Osman Mohamud of the town of Corvallis, a naturalized US citizen of Somali descent, who will appear in court on Monday.
Mohamud was arrested Friday evening after he tried to remotely detonate what he thought was an explosives-laden van parked near the tree ceremony, which went ahead in state capital Portland's Pioneer Courthouse Square.
But the device was in fact a fake supplied by undecover agents from the Federal Bureau of Investigation, and the public was never in any danger, they added.
"The threat was very real. Our investigation shows that Mohamud was absolutely committed to carrying out an attack on a very grand scale," said Arthur Balizan, a special agent in charge of the FBI in Oregon.
According to court documents, Mohamud exchanged emails with a contact in Pakistan's northwest frontier province late last year, and discussed the possibility of Mohamud traveling to Pakistan to engage in jihad.
This man allegedly referred Mohamud to a second conspirator overseas and gave Mohamud a name and email address.
But he was unable to make contact with him, until in June this year an FBI undercover agent contacted Mohamud, pretending to be an associate of his Pakistani contact.
Mohamud and the FBI agent then agreed to meet in Portland in July, when the Somali said he had written articles that were published in "Jihad Recollections", an online magazine urging violence against non-Muslims.
He later told undercover agents that he had been thinking of conducting a holy war against infidels since the age of 15, and suggested the plot to bomb Friday's traditional pre-Christmas ceremony in Portland.
FBI operatives cautioned Mohamud several times about the seriousness of this plan, noting that there would be many children at the event.
But Mohamud responded that he was looking for a "huge mass that will ... be attacked in their own element with their families celebrating the holidays," the documents noted.
In subsequent months, Mohamud mailed bomb components to the undercover FBI operatives, who he believed were assembling the device, as well as passport photos as part of a plan to help him sneak out of the country after the attack.
Earlier this month, Mohamud and the undercover FBI operatives traveled to a remote location in Lincoln County, Oregon, where they detonated a bomb concealed in a backpack as a rehearsal of the upcoming attack.
"I want whoever is attending that event to leave, to leave either dead or injured," Mohamud said of the Christmas tree ceremony, according to the court documents.
That same day, he recorded a video, in which he read a written statement that offered a rationale for his bomb attack.
On Thursday last week Mohamud "showed the (undercover agents) the locations he had identified to park the bomb, specifically identifying the spot that he thought would inflict the most casualties."
On Friday afternoon, hours before the planned attack, Mohamud met the undercover agents to make the final preparations.
"Mohamud went and looked at the bomb, which was in the back of a large white van. When Mohamud saw the bomb, he told the (undercover agents) it was "˜beautiful'," said the affidavit.
Former FBI assistant director Thomas Fuentes said the choice of Oregon was particularly alarming for ordinary Americans.
"Everybody right now expects the attack to occur either in New York City, or Washington DC, or at least a major city of the United States," he told CNN.
"To have it occur in somewhere that's not New York is an issue, because then everybody can wonder whether or not somebody in their neighborhood is plotting to do something like this in their community," he added.
Mohamud is expected to make his initial appearance in federal court in Portland on Monday.