The Obama administration used DNA testing and other means to confirm that elite American forces in Pakistan had in fact killed Osama bin Laden, the mastermind behind the Sept. 11, 2001 terrorist attacks, officials said Monday, as the world absorbed the stunning news.

The officials said the DNA testing alone offered a “99.9 percent” 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 physical features like bin Laden’s height all helped confirmed the identification.

One official said there should be no doubt in anybody’s mind that the person killed was bin Laden.

The officials spoke on condition of anonymity given the sensitivity 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 administration officials were weighing the merit and appropriateness of releasing a photo of bin Laden, who was shot in the head.

The face of global terrorism was killed in a firefight with American forces. As spontaneous celebrations and expressions of relief gave way to questions about precisely what happened and what comes next, U.S. officials warned that the campaign against terrorism is not nearly over — and that the threat of retaliation was real.

“The fight continues and we will never waver,” Secretary of State Hillary Rodham Clinton said Monday. Her comments had echoes of former President George W. Bush’s declaration nearly a decade ago, when al-Qaida attacks against America led to war in Afghanistan 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’s killing in a dramatic White House statement late Sunday. “Justice has been done,” he said.

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

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

The military operation that ended bin Laden’s life took mere minutes, and there were no U.S. casualties.

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