The White House has dismissed a fresh audio message thought to be from Osama Bin Laden, and pledged once again to track down the al-Qaeda leader.
Rumours about the state of Bin Laden's health have abounded
US Vice-President Dick Cheney rejected an apparent offer of a "long-term truce", describing it as a "ploy".
Arabic TV station al-Jazeera aired the tape, later authenticated by the CIA.
The message contained threats of new attacks within the US and abroad, but US security officials said they would not raise the national threat level.
It is the first time Bin Laden has been heard from since December 2004.
Analysts believe the tape dates from at least 22 November as the speaker refers to reports that President Bush planned to bomb al-Jazeera's headquarters in Qatar.
Stick and carrot
Speaking on the Fox News TV network, Mr Cheney said it was too early to draw firm conclusions about the tape, but added that al-Qaeda was "unlikely" ever to sit down and sign a truce.
"I think you have to destroy them. It's the only way with them," the vice-president said.
In the audio message, Bin Laden appeared to suggest that a US withdrawal from Muslim lands could prompt agreement over a truce.
But the speaker also threatened fresh attacks in the US, as well as a continuation of strikes within Iraq.
In his message, the man purported to be Bin Laden referred to the allegation of a US plan to attack al-Jazeera, calling Mr Bush "the butcher of freedom in the world".
The speaker on the tape said the reason there had not been an attack in the US since 11 September 2001 was not because of superior US security, but because the group had been engaged in activities in Iraq - and because operations in the US "need preparations".
"The operations are happening in Baghdad and you will see them here at home the minute they are through (with preparations), with God's permission," he said.
On Fox News, Mr Cheney said: "Obviously no-one can guarantee that we won't be hit again. But our nation has been protected by more than luck."
US officials have said they believe Bin Laden is hiding in a mountainous area on the border between Pakistan and Afghanistan.
In a video message broadcast last month, al-Qaeda's number two Ayman al-Zawahiri declared that Bin Laden was alive despite a prolonged absence and rumours about ill-health or possible injury.
The offer of a truce came in light of the fact that US public opinion polls now show growing opposition to the war in Iraq.
"We have no objection to responding to this with a long-term truce based on fair conditions," the speaker said.
"We do not mind offering you a truce that is fair and long-term... so we can build Iraq and Afghanistan... there is no shame in this solution because it prevents wasting of billions of dollars.
"Your president is misinterpreting public opinion polls which show that the vast majority of you support the withdrawal of your forces from Iraq."
White House spokesman Scott McClellan quickly dismissed the truce offer saying: "We do not negotiate with terrorists. We put them out of business".
Bin Laden offered Europe a similar pact following the Madrid train bombings of March 2004.
Correspondents say it is an attempt to frighten the public and drive a wedge between them and their governments, which say it is necessary to stay to distance in Iraq, not pull out troops.
The BBC's Justin Webb in Washington says that in the US the immediate political effect of the tape will probably be to boost support for President George W Bush.