WASHINGTON - (AP) - The Obama administration used DNA testing andother means to confirm that elite American forces in Pakistan hadin fact killed Osama bin Laden, the mastermind behind the Sept. 11,2001 terrorist attacks, officials said Monday, as the worldabsorbed the stunning news.

The officials said the DNA testing alone offered a "99.9percent" certainty that bin Laden was shot dead in a daring U.S.military operation. Detailed photo analysis by the CIA,confirmation by other people at the raid site and matching physicalfeatures like bin Laden's height all helped confirmed theidentification.

One official said there should be no doubt in anybody's mindthat the person killed was bin Laden.

The officials spoke on condition of anonymity given thesensitivity of the matter.

Still, it was unclear if the world would ever get visual proof.Bin Laden's body was quickly buried at sea, and administrationofficials were weighing the merit and appropriateness of releasinga photo of bin Laden, who was shot in the head.

The face of global terrorism was killed in a firefight withAmerican forces. As spontaneous celebrations and expressions ofrelief gave way to questions about precisely what happened and whatcomes next, U.S. officials warned that the campaign againstterrorism is not nearly over - and that the threat of retaliationwas real.

"The fight continues and we will never waver," Secretary ofState Hillary Rodham Clinton said Monday. Her comments had echoesof former President George W. Bush's declaration nearly a decadeago, when al-Qaida attacks against America led to war inAfghanistan and changed the way Americans viewed their own safety.

Turning to deliver a direct message to bin Laden's followers,she vowed: "You cannot wait us out."

President Barack Obama himself delivered the news of bin Laden'skilling in a dramatic White House statement late Sunday. "Justicehas been done," he said.

The president was expected to address the topic again in a Medalof Honor ceremony shortly before noon EDT.

Officials say CIA interrogators in secret overseas prisonsdeveloped the first strands of information that ultimately led tothe killing of Osama bin Laden.

The military operation that ended bin Laden's life took mereminutes, and there were no U.S. casualties.

U.S. Blackhawk helicopters ferried about two dozen troops fromNavy SEAL Team Six, a top military counter-terrorism unit, into thecompound identified by the CIA as bin Laden's hideout - and backout again in less than 40 minutes. Bin Laden was shot in the head,officials said, after he and his bodyguards resisted the assault.

Three adult males were also killed in the raid, including one ofbin Laden's sons, whom officials did not name. One of bin Laden'ssons, Hamza, is a senior member of al-Qaida. U.S. officials alsosaid one woman was killed when she was used as a shield by a malecombatant, and two other women were injured.

The compound is about a half-mile from a Pakistani militaryacademy, in a city that is home to three army regiments andthousands of military personnel. Abbottabad is surrounded by hillsand with mountains in the distance.

Critics have long accused elements of Pakistan's securityestablishment of protecting bin Laden, though Islamabad has alwaysdenied it, and in a statement the foreign ministry said his deathshowed the country's resolve in the battle against terrorism.

The U.S. official who disclosed the burial at sea said it wouldhave been difficult to find a country willing to accept theremains. Obama said the remains had been handled in accordance withIslamic custom, which requires speedy burial.

"I heard a thundering sound, followed by heavy firing. Thenfiring suddenly stopped. Then more thundering, then a big blast,"said Mohammad Haroon Rasheed, a resident of Abbottabad, Pakistan,after the choppers had swooped in and then out again.

Bin Laden's death came 15 years after he declared war on theUnited States. Al-Qaida was also blamed for the 1998 bombings oftwo U.S. embassies in Africa that killed 224 people and the 2000attack on the USS Cole that killed 17 American sailors in Yemen, aswell as countless other plots, some successful and some foiled.

"We have rid the world of the most infamous terrorist of ourtime," CIA director Leon Panetta declared to employees of theagency in a memo Monday morning. He warned that "terrorists almostcertainly will attempt to avenge" the killing of a man deemeduncatchable. "Bin Laden is dead. Al-Qaida is not," Panetta said.

Retaliatory attacks against the U.S. and Western targets couldcome from members of al-Qaida's core branch in the tribal areas ofPakistan, al-Qaida franchises in other countries, and radicalizedindividuals in the U.S. with al-Qaida sympathies, according to aHomeland Security Department intelligence alert issued Sunday andobtained by The Associated Press.

While the intelligence community does not have insight intocurrent al-Qaida plotting, the department believes symbolic,economic and transportation targets could be at risk, and smallarms attacks against other targets can't be ruled out.

In all, nearly 3,000 were killed in the Sept. 11 attacks.

As news of bin Laden's death spread, hundreds of people cheeredand waved American flags at ground zero in New York, the site whereal-Qaida hijacked jets toppled the twin towers of the World TradeCenter. Thousands celebrated all night outside the White Housegates.

As dawn came the crowd had thinned yet some still flowed in tobe a part of it. A couple of people posed for photographs in frontof the White House while holding up front pages of Monday'snewspapers announcing bin Laden's death.

The development seems certain to give Obama a political lift asthe nation swelled in pride. Even Republican critics lauded him.

But its ultimate impact on al-Qaida is less clear.

The greatest terrorist threat to the U.S. is now considered tobe the al-Qaida franchise in Yemen, far from al-Qaida's core inPakistan. The Yemen branch almost took down a U.S.-bound airlineron Christmas 2009 and nearly detonated explosives aboard two U.S.cargo planes last fall. Those operations were carried out withoutany direct involvement from bin Laden.

The few fiery minutes in Abbottabad followed years in which U.S.officials struggled to piece together clues that ultimately led tobin Laden, according to an account provided by senioradministration officials who spoke on condition of anonymitybecause of the sensitivity of the operation.

Based on statements given by U.S. detainees since the 9/11attacks, they said, intelligence officials have long known that binLaden trusted one al-Qaida courier in particular, and they believedhe might be living with him in hiding.

Four years ago, the United States learned the man's identity,which officials did not disclose, and then about two years later,they identified areas of Pakistan where he operated. Last August,the man's residence was found, officials said.

"Intelligence analysis concluded that this compound was custombuilt in 2005 to hide someone of significance," with walls as highas 18 feet and topped by barbed wire, according to one official.Despite the compound's estimated $1 million cost and two securitygates, it had no phone or Internet running into the house.

By mid-February, intelligence from multiple sources was clearenough that Obama wanted to "pursue an aggressive course ofaction," a senior administration official said. Over the next twoand a half months, the president led five meetings of the NationalSecurity Council focused solely on whether bin Laden was in thatcompound and, if so, how to get him, the official said.

Obama made a decision to launch the operation on Friday, shortlybefore flying to Alabama to inspect tornado damage, and aides setto work on the details.

Panetta was directly in charge of the military team during theoperation, according to one official, and when he and his aidesreceived word at agency headquarters that bin Laden had beenkilled, cheers broke out around the conference room table.

Administration aides said the operation was so secretive that noforeign officials were informed in advance, and only a small circleinside the U.S. government was aware of what was unfolding half aworld away.

In his announcement, Obama said he had called PakistaniPresident Asif Ali Zardari after the raid, and said it was"important to note that our counter-terrorism cooperation withPakistan helped lead us to bin Laden and the compound where he washiding."VIDEO: President Obama announces Osama bin Laden's death VIDEO: Phone interview with Rep. King on bin Laden death Text of President Barack Obama's announcement