Underwear bomber pleads guilty:

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  Law enforcement officials guard the Federal Courthouse in Detroit where Umar Farouk …
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  Umar Farouk Abdulmutallab pictured in this 2009 booking photograph released by the …

A Nigerian man dubbed the "underwear bomber" pleaded guilty Wednesday to trying to blow up a US-bound airliner on Christmas Day 2009, saying he had sought to avenge the killing of Muslims.

In a six-minute speech to a shocked courtroom on the second day of his high profile-trial in Detroit, Michigan, Umar Farouk Abdulmutallab insisted his actions were righteous and that the true crime was US foreign policy.

"I am guilty of this count in US law but not in the Koran," the 25-year-old Nigerian said as he reversed course in the trial and confessed to trying to kill 289 people on a packed transatlantic flight using explosives hidden in his underwear.

"The United States should be warned that if they continue and persist in promoting the blasphemy of Mohammed and the US continues to kill and support those who kill innocent Muslims then the US should await a great calamity through the hands of the Mujahedeen... or God."

The botched plot, which US officials say was the work of Al-Qaeda in the Arabian Peninsula, failed because the explosives did not fully detonate and instead caused a fireball.

Passengers and crew members were able to restrain Abdulmutallab and put out the fire as the Northwest flight from Amsterdam made an emergency landing in Detroit on December 25, 2009.

The eight terrorism counts he pleaded guilty to cumulatively carry a mandatory sentence of life in prison without the possibility of parole.

The botched operation triggered global alarm and led the United States to adopt stringent new screening and security measures.

The reputation of the US intelligence services also took a hit because Abdulmutallab's father, a prominent Nigerian banker, had warned the CIA about his son's growing radicalization.

Republicans capitalized on the missteps and the revived fears to paint President Barack Obama as weak on terror, as well as to undermine his plans for shutting down Guantanamo Bay and prosecuting Khalid Sheikh Mohammed and other high-profile "enemy combatants" being held there in US civilian courts.

They are currently pushing legislation that would ensure that any terror suspects who are not US citizens be handed over to the military rather than be prosecuted by civil law enforcement and the courts.

Attorney General Eric Holder hailed the guilty plea for removing "any doubt that our courts are one of the most effective tools we have to fight terrorism and keep the American people safe."

"We will continue to be aggressive in our fight against terrorism and those who target us, and we will let results, not rhetoric, guide our actions," Holder said in a statement.

The head of the FBI's Detroit field office said the case showed that civilian law enforcement is the best way to handle domestic terrorism cases.

There were no military officials among the hundreds of agents and officers who rushed to the airport on that Christmas Eve, he noted.

"We operate under the rules of engagement of the US constitution that we were sworn to uphold," Andrew Arena told reporters.

"We did get actionable intelligence that day and in the days after that."

The abrupt end to the trial means that many questions -- including the degree of involvement of slain Al-Qaeda preacher Anwar al-Awlaqi -- remain unanswered.

Abdulmutallab kept his description of how he carried out the plot to the absolute minimum required to satisfy the judge that he was indeed guilty of all charges. Every admission included an accusation.

Abdulmutallab said he "had an agreement with at least one person" to attack the US in retaliation for US support for Israel and in revenge for the killing of innocent Muslims in Palestine, Yemen, Iraq, Somalia, Afghanistan and beyond.

"I attempted to use an explosive device, which under US law is called a weapon of mass destruction, which I call a blessed weapon to save the lives of innocent Muslims for the US used weapons of mass destruction on innocent Muslims," he told the court. He is to be sentenced on January 12.

His court-appointed standby counsel said he had urged the young man to see the trial through but Abdulmutallab was not interested in trying to avoid spending the rest of his life behind bars.

"He wanted to say something for some time and that was satisfying to him," Anthony Chambers told reporters.