Al-Qaeda mastermind Osama bin Laden was killed Sunday in a firefight with covert US forces deep inside Pakistan, prompting President Barack Obama to declare "justice has been done" a decade after the September 11 attacks.
The death of the reviled US enemy, after a massive manhunt, sparked jubilation across the United States, with a huge crowd gathering outside the White House just before midnight, chanting "USA, USA" and waving American flags as Obama made a sudden and dramatic nationwide address to Americans.
"Tonight, I can report to the American people and to the world that the United States has conducted an operation that killed Osama bin Laden, the leader of Al-Qaeda, and a terrorist who's responsible for the murder of thousands of innocent men, women and children," Obama said.
Obama said in the historic speech from the White House that he had directed US armed forces to launch an attack against a compound in Abbottabad, Pakistan on Sunday acting on a lead that first emerged last August.
"A small team of Americans carried out the operation with extraordinary courage and capability. No Americans were harmed. They took care to avoid civilian casualties.
"After a firefight, they killed Osama bin Laden and took custody of his body," the US leader said.
"Justice has been done."
Bin Laden's demise marks the biggest triumph yet in the 10-year US war against terrorism launched after the September 11 attacks, which saw America embroiled in two wars, and changed many aspects of US life.
The operation will also likely go down as one of the most spectacular intelligence operations in US history, and provide a huge morale boost the oft-criticized US covert community.
Former US president George W. Bush who was in office at the time of the September 11 attacks said bin Laden's death was a "momentous" achievement and congratulated Obama and US intelligence and military forces.
"This momentous achievement marks a victory for America, for people who seek peace around the world, and for all those who lost loved ones on September 11, 2001," Bush said in a statement.
"The fight against terror goes on, but tonight America has sent an unmistakable message: No matter how long it takes, justice will be done."
Pakistani intelligence officials also confirmed bin Laden's death.
Obama said he had called Pakistani President Asif Ali Zardari after bin Laden's death and said cooperation with the uneasy US anti-terror ally had helped lead American forces to bin Laden.
US armed forces have been hunting the Saudi terror kingpin for years, an effort that was redoubled following the attacks by hijacked airliners on the World Trade Center in New York and the Pentagon which killed nearly 3,000 people in 2001.
A fourth passenger jet crashed in a remote area of Pennsylvania, apparently brought down after passengers revolted and tried to prevent it from reaching its target, assumed to be Washington.
Until Sunday, bin Laden had always managed to evade US armed forces and a massive manhunt, and was most often thought to be hiding out in Pakistan and Afghanistan border areas.
The death of bin Laden will raise huge questions about the future shape of Al-Qaeda and also have steep implications for US security and foreign policy 10 years into a global anti-terror campaign.
It will also provoke fears that the United States and its allies will face retaliation from supporters of bin Laden and other Islamic extremist groups.
Bin Laden's demise will also cast a new complexion on the increasingly unpopular war in Afghanistan, where 100,000 troops are still battling the Taliban and Al-Qaeda after a decade of war.
Bush first said he wanted bin Laden "dead or alive" in the weeks after the September 11 attacks.
Bin Laden was top of America's most wanted list, and was blamed by Washington for masterminding a string of other attacks, including the attacks on US embassies in Kenya and Africa in 1998.
He frequently taunted Bush, and Obama after he took office in 2009, with taped messages.
The US dollar rose against the euro and the yen when it emerged that Obama would announce bin Laden's death.
The dollar went up against the euro, which fetched 1.4764 dollars from 1.4864 in earlier trade. The dollar was at 81.66 yen from 81.19 earlier.
The news was welcomed by Americans across the country, even though bin Laden's death was only confirmed shortly before midnight Sunday.
"I'm proud to be an American tonight," Kenneth Specht, a New York firefighter on 9/11, told CNN, paying tribute to the victims of the attacks in New York and Washington.
"Tonight they are first and foremost in our minds," he said.
Amid fears of retaliation by Al-Qaeda or other groups, the US State Department issued a global travel alert to all US citizens.
"The US Department of State alerts US citizens traveling and residing abroad to the enhanced potential for anti-American violence given recent counter-terrorism activity in Pakistan," it said in a statement.
New York's police chief Raymond Kelly meanwhile called the killing of bin Laden a "welcome milestone" for the families of the victims of the September 11 attacks.