QUANTICO, Virginia - On the eve of the second anniversary of the Sept. 11 attacks, President George W. Bush warned on Wednesday that al Qaeda was still plotting against Americans and must be hunted down and defeated.
His remarks came as a new al Qaeda audiotape vowed further attacks on US targets.
"The memories of September 11th will never leave us. We will not forget the burning towers and the last phone calls and the smoke over Arlington," Bush said in speech at a FBI laboratory.
"And we will never forget the servants of evil who plotted the attacks. And we will never forget those who rejoiced at our grief and our mourning," Bush said.
Wednesday's speech was Bush's major address commemorating the anniversary of the attacks on the World Trade Centre and the Pentagon, which killed about 3000 people.
On Thursday, he is to mark the occasion by attending a memorial service, observing a moment of silence on the White House South lawn, and visiting wounded soldiers.
Bush did not refer to the new al Qaeda message, purported to be from Osama bin Laden and his deputy, Ayman al-Zawahri, and he told reporters before delivering his remarks that he had not yet heard the audiotape.
But he said the threat from al Qaeda was real.
"The forces of global terror cannot be appeased, and they can't be ignored. They must be hunted, they must be found and they will be defeated," he said.
"The enemy is wounded but still resourceful and actively recruiting and still dangerous. We cannot afford a moment of complacency," Bush added.
Bush did not mention bin Laden by name.
The president touts the 2001 war in Afghanistan and the war in Iraq earlier this year as major accomplishments in the administration's "war on terrorism."
However, critics of the Iraq war have pointed out that the administration has yet to prove a link between deposed Iraqi leader Saddam Hussein and al Qaeda, accused of masterminding the Sept. 11 attacks.
Bush gave a major address on Sunday night in which he asked Congress for an US$87 billion ($151.09 billion) package for Iraq's reconstruction and linked the need to stay the course in Iraq to the fight against terrorism.
On the Arabic network Al Jazeera, a voice said to be bin Laden's praised the suicide hijackers who carried out the September 11 attacks while a separate audiotape, purportedly of Zawahri, promised more attacks on the United States.
Intelligence experts were reviewing the tapes to determine their authenticity and had drawn no final conclusions.
"It's a reminder of what we know that these terrorists continue to plot, to attack us and to attack freedom," said Sean McCormack, spokesman for the White House National Security Council.