The President of the United States has described the destruction caused in New York and Washington as an act of war against all freedom-loving people.
In a statement broadcast at 1053 local time (1553 BST), George Bush vowed the US would use all its resources to avenge the worst-ever attacks on American soil.
But he warned an angry and wounded nation they would have to be patient and said any action could be a monumental struggle.
The president has also been seeking the backing of world leaders for an international campaign against terrorism.
As the estimated number of dead rose into the thousands the day after the tragedy, members of the US government began talking openly of war.
US Secretary of State Colin Powell said: “It isn’t going to be solved with a single counter-attack against one individual, it’s going to be a long term conflict.”
Expressions of support have come quickly from American allies, and also from countries not known for their sympathy with the US – the leaders of Libya and Palestine both condemned the attacks in the strongest terms.
Only Iraq has endorsed the atrocity, saying the attacks were a “lesson for all tyrants and oppressors” and the fruit of American crimes.
Tony Blair offered the unequivocal backing of the UK, echoing President Bush’s words in his press conference announcing the recall of Parliament.
“I don’t think there is any doubt at all that this threat is aimed at the whole democratic world,” the prime minister told reporters.
“The US has been singled out… But these terrorists will regard us all as targets.”
Courtesy BBC News
The criminal investigation quickly identified the hijackers, and linked them to al-Qaeda – the Islamic militant group set up by the Afghanistan-based Osama Bin Laden.
President Bush’s “War on Terror” began on 8 October 2001 with an air bombardment of Afghanistan by US and UK forces.
With the help of the Northern Alliance opposition group, the Taleban leaders of the country were quickly toppled.
Many alleged members of al-Qaeda were caught and flown to a US base on Cuba, but Bin Laden proved to be more elusive and the hunt for him took almost 10 years.
In April 2011, President Obama ordered a covert operation to kill or capture Bin Laden. On May 2, 2011, the White House announced that U.S. Navy SEALs had successfully carried out the operation, killing Bin Laden in his Abbottabad compound in Pakistan.