DNA tests on the body of Osama Bin Laden showed a virtual 100 percent match to relatives, and a woman believed to be his wife also identified him by name, a senior U.S. intelligence official told reporters Monday.
The United States was now reviewing a large cache of materials seized at the compound in Pakistan where U.S. forces killed Bin Laden, the official said, speaking on condition of anonymity to reporters.
"Those materials are currently being exploited and analyzed and a task force is being set up at CIA ... given the volume of materials collected at the raid site," the official said.
A small U.S. strike team, dropped by helicopter to Bin Laden's compound near the Pakistani capital Islamabad under the cover of night, shot dead the al Qaeda leader in a firefight, U.S. officials said.
"This was a kill operation," one security official told Reuters, but added: "If he had waved a white flag of surrender he would have been taken alive."
The revelation that Bin Laden was living in a multi-million dollar, three-story residence in the military garrison town of Abbottabad, and not as many had speculated, in the country's lawless western border regions, is a huge embarrassment to Pakistan, whose relations with Washington have frayed under the Obama administration.
President Barack Obama, whose popularity suffered from continuing U.S. economic woes, will likely see a short-term bounce in his approval ratings. At the same time, he is likely to face mounting pressure from Americans to speed up the planned withdrawal this July of U.S. forces from Afghanistan.
However, Bin Laden's death is unlikely to have any impact on the nearly decade-long war in Afghanistan, where U.S. forces are facing record violence by a resurgent Taliban. Many analysts see Bin Laden's death as largely symbolic since he was no longer believed to have been issuing operational orders to the many autonomous al Qaeda affiliates around the world.
Still, Obama, speaking at a ceremony at the White House, said the world was a better place after the al Qaeda leader's death, and that the U.S. had kept its commitment to see that justice was done.
Financial markets were more optimistic. The dollar and stocks rose, while oil and gold fell, on the view Bin Laden's death reduced global security risks.
Warnings of Al Qaeda Revenge
Still, fearful of revenge attacks, the United States swiftly issued security warnings to Americans worldwide. CIA Director Leon Panetta said al Qaeda would "almost certainly" try to avenge Bin Laden's death.
"Though Bin Laden is dead, al Qaeda is not. The terrorists almost certainly will attempt to avenge him, and we must—and will—remain vigilant and resolute," Panetta said.
France's President Nicolas Sarkozy hailed the killing as a coup in the fight against terrorism, but he, too, warned it did not spell al Qaeda's demise.
British Prime Minster David Cameron said the West would have to be "particularly vigilant" in the weeks ahead.
A source familiar with the operation said Bin Laden was shot in the head after the U.S. military team, which included members of the Navy's elite Seals unit, stormed the compound. Television pictures from inside the house showed bloodstains smeared across a floor next to a large bed.
Buried at Sea
Two officials, speaking on condition of anonymity, said Bin Laden was buried at sea from the deck of a U.S. aircraft carrier. A third official said this was done to prevent a gravesite on land becoming a shrine for followers.
Bin Laden's body was washed according to Islamic custom and he received a religious funeral, a according to a defense official.
"Preparations for at-sea burial began at 1:10 a.m. EST and were completed at 2 a.m. EST," the official said. "Traditional procedures for Islamic burial were followed."
"The deceased's body was washed and then placed in a white sheet. The body was placed in a weighted bag. A military officer read prepared religious remarks which were translated into Arabic by a native speaker. After the words were complete, the body was place on a prepared flat board, tipped up, whereupon the deceased's body eased into the sea," the official said.
Security Victory for Obama
It was the biggest national security victory for the president since he took office in early 2009 and will make it difficult for Republicans to portray Democrats as weak on security as he seeks re-election in 2012.
In sharp contrast to the celebrations in America, on the streets of Saudi Arabia, Bin Laden's native land, there was a mood of disbelief and sorrow among many. The Palestinian Islamist group Hamas mourned Bin Laden as an "Arab holy warrior."
But many in the Arab world felt his death was long overdue.
For many Arabs, inspired by the popular upheavals in Egypt, Libya and elsewhere over the past few months, the news of Bin Laden's death had less significance than it once might have.
Pakistan Told After Raid
The operation could complicate relations with Pakistan, a key U.S. ally in the battle against militancy and the war in Afghanistan. Those ties have already been damaged over U.S. drone strikes in the west of the country and the six-week imprisonment of a CIA contractor earlier this year.
Pakistani authorities were told the details of the raid only after it had taken place, highlighting the lack of trust between Washington and Islamabad.
"For some time there will be a lot of tension between Washington and Islamabad because Bin Laden seems to have been living here close to Islamabad," said Imtiaz Gul, a Pakistani security analyst.
Walls Topped With Barbed Wire
Bin Laden was finally found after U.S. forces discovered in August 2010 that one of his most trusted couriers lived in an unusual and high-security building in Pakistan that had few outward facing windows and no Internet or telephone access. Also, despite the couriers having little sources of wealth, the property was valued at more than a million dollars.
Intense security measures included 12- to 18-foot (3.6 meters to 5.5 meters) outer walls topped with barbed wire and internal walls that sectioned off different parts of the compound, officials said. Two security gates restricted access, and residents burned their trash, rather than leaving it for collection as did their neighbors, officials said.
"When we saw the compound where the brothers lived, we were shocked by what we saw: an extraordinarily unique compound," a senior administration official said.
"The bottom line of our collection and our analysis was that we had high confidence that the compound harbored a high-value terrorist target. The experts who worked this issue for years assessed that there was a strong probability that the terrorist who was hiding there was Osama Bin Laden," another administration official said.
The building, about eight times the size of other nearby houses, sat on a large plot of land that was relatively secluded when it was built in 2005. When it was constructed, it was on the outskirts of Abbotabad's center, at the end of a dirt road, but some other homes have been built nearby in the six years since it went up, officials said.
U.S. analysts realized that a third family lived there in addition to the two brothers, and the age and makeup of the third family matched those of the relatives—including his youngest wife—they believed would be living with Bin Laden.
"Everything we saw, the extremely elaborate operational security, the brothers' background and their behavior and the location of the compound itself was perfectly consistent with what our experts expected Bin Laden's hide-out to look like," another Obama administration official said.
A small U.S. team conducted a helicopter raid on the compound on Sunday afternoon, officials said. After 40 minutes of fighting, Bin Laden and an adult son, one unidentified woman and two men—identified as the courier and his brother—were dead, officials said.
After the raid was reported, thousands of cheering and flag-waving people converged on the White House. Similar celebrations erupted at New York's Ground Zero, site of the World Trade Center twin towers destroyed on Sept. 11.
"I never figured I'd be excited about someone's death. It's been a long time coming," said firefighter Michael Carroll, 27, whose firefighter father died in the Sept. 11 attacks.
Former President George W. Bush, whose eight-year presidency was defined by the Sept. 11 attacks after he launched a global "war on terror" to root out Islamic militants, called the operation a "momentous achievement".