DETROIT (AP) -- A Nigerian man said Wednesday he tried to bring down an international flight over Detroit with a bomb in his underwear in retaliation for the killing of Muslims worldwide, taking a federal court by surprise as he pleaded guilty on the second day of his trial.

Umar Farouk Abdulmutallab, who had never denied the accusations against him, calmly answered questions from U.S. District Judge Nancy Edmunds before pleading guilty to all eight charges he faced, including conspiracy to commit terrorism and attempted use of a weapon of mass destruction.

He then told the courtroom that the underwear bomb was a ``blessed weapon to save the lives of innocent Muslims.''

``I intended to wreck a U.S. aircraft for the U.S. wreckage of Muslim lands and property,'' Abdulmutallab said.

Outside court, defense attorney Anthony Chambers said Abdulmutallab, who had chosen to represent himself and was being assisted by Chambers, pleaded guilty against the lawyer's wishes.

``We wanted to continue the trial but we respect his decision,'' Chambers said.

Abdulmutallab, who told the judge he is 25, said he carried a bomb in his underwear onto Northwest Airlines Flight 253 on Christmas 2009 with the intention of killing the nearly 300 people on board. The bomb didn't work, and passengers jumped on Abdulmutallab when they saw smoke and fire.

Prosecutors' evidence was stacked high. Abdulmutallab was badly burned in a plane full of witnesses. The government said he told FBI agents he was working for al-Qaida and directed by Anwar al-Awlaki, a radical, American-born Muslim cleric recently killed by the U.S. in Yemen. There were also photos of his scorched shorts as well as video of Abdulmutallab explaining his suicide mission before departing for the U.S.

In September 2010, Abdulmutallab suggested he wanted to plead guilty to some charges. But he didn't, and instead dropped his four-lawyer, publicly financed defense team and decided to represent himself. He said relying on others wasn't in his best interest.

His lawyers at the time said they had talked to prosecutors about a possible plea deal. Abdulmutallab had asked the judge what he needed to do to plead guilty to some charges. She referred him to Chambers.

Abdulmutallab had written a few court filings in his own hand, including a request to be judged by Islamic law. He at times appeared agitated in court, declaring that Osama bin Laden and al-Awlaki are alive. He also objected to trial testimony from experts would have discussed al-Qaida and martyrdom.

On Tuesday, passengers on Flight 253 testified that Abdulmutallab took a long bathroom break in the plane, during which prosecutors say he was preparing for death.

He took a small bag to the bathroom and was gone 10 to 15 minutes, according to passenger Mike Zantow, the first witness in Abdulmutallab's terrorism trial.

``I thought he was freshening up for arrival in Detroit. ... We had less than an hour to go,'' Zantow said.

Assistant U.S. Attorney Jonathan Tukel said the son of a wealthy Nigerian banker believed his calling that day was martyrdom.

``He was preparing to die and enter heaven,'' Tukel said. ``He purified himself. He washed. He brushed his teeth. He put on perfume.''

After returning to his seat, Abdulmutallab pushed a syringe plunger into the chemical bomb, an action that produced a loud ``pop'' sound, then flames and smoke, the prosecutor said.

``Then all hell broke loose. While the fireball was on him, the defendant sat there. He didn't move. He was expressionless. He was completely blank,'' Tukel said.

The government says Abdulmutallab willingly explained the plot twice, first to U.S. border officers who took him off the plane and then in more detail to FBI agents who interviewed him at a hospital for 50 minutes, following treatment for serious burns to his groin.

Abdulmutallab told authorities he trained in Yemen, home base for Al-Qaida in the Arabian Peninsula, and was influenced by al-Awlaki, who was killed in a Sept. 30 U.S. military air strike.

Following the strike, a U.S. official outlined new details of al-Awlaki's involvement against the U.S., including Abdulmutallab's alleged mission. The official, who spoke on condition of anonymity to discuss intelligence matters, said al-Awlaki specifically directed Abdulmutallab to detonate an explosive device over U.S. airspace to maximize casualties.

Officials have said al-Awlaki was believed to be at a gathering of al-Qaida figures in Yemen's Shabwa mountains a day before the attack, after which Osama bin Laden appeared in a video declaring Abdulmutallab a ``hero.'' Abdulmutallab also has been lauded by al-Qaida's English-language Web magazine Inspire, whose editor was killed along with al-Awlaki.