According to the New York Times, "Prosecutors and federal agents seemed stunned, if pleased, and declared that the plea was evidence that the American court system, as opposed to a military tribunal, could bring a suitable outcome to a terrorism case."
The New York Times story continued:
Almost two years after fellow passengers flying aboard Northwest Airlines Flight 253 watched in panic and confusion as smoke and flames rose from Mr. Abdulmutallab’s lap, he pleaded guilty to eight federal crimes, including conspiracy to commit an act of terrorism, attempted murder and attempted use of a weapon of mass destruction. He was offered no deal from prosecutors in exchange for his plea. He faces sentencing in January, but prosecutors said the nature of some of the crimes he pleaded guilty to automatically required a life sentence with no chance of parole.
The choice appeared less a strategic legal calculation than an opportunity for Mr. Abdulmutallab, who has described himself as a member of Al Qaeda and who prosecutors say conspired in his plan with other members of Al Qaeda, to make a public statement certain to reach a wide audience.
After telling Judge Nancy G. Edmunds that he was indeed pleading guilty to each count against him, Mr. Abdulmutallab read a statement that he had written saying that his behavior may have violated American law but that it was in keeping with Muslim law, and that his efforts to harm Americans were retribution for American acts around the world.
“I attempted to use an explosive device which in the U.S. law is a weapon of mass destruction, which I call a blessed weapon to save the lives of innocent Muslims, for U.S. use of weapons of mass destruction on Muslim populations in Afghanistan, Iraq, Yemen and beyond,” Mr. Abdulmutallab, a Nigerian citizen in his 20s, said quietly and calmly. In repeated appearances in court, Mr. Abdulmutallab, the well-educated son of a wealthy family, has almost seemed to have two personas: a polite, silent observer who appeared small at the defense table, and an unruly onlooker who would suddenly yell out messages of support for Osama bin Laden and Anwar al-Awlaki, who was recently killed by a missile from an American drone. The American authorities have described him as a leading figure in a Qaeda affiliate in Yemen.
“If you laugh at us now,” he said Wednesday, during the statement in open court that went on for several minutes, “we will laugh at you later.”
...In Washington, Eric H. Holder Jr., the attorney general, issued a statement on the verdict. “Contrary to what some have claimed, today’s plea removes any doubt that our courts are one of the most effective tools we have to fight terrorism and keep the American people safe,” he said. “Our priority in this case was to ensure that we arrested a man who tried to do us harm, that we collected actionable intelligence from him and that we prosecuted him in a way that was consistent with the rule of law.”
In an article I published last year, I discuss some of the motivations behind terrorist suspects pleading guilty. The article is available here.