It could take days before the U.S. government can say for sure that a new Osama bin Laden tape is really that of the al-Qaida leader.
In the past, CIA analyses of such messages have taken a day or two to complete.
The new videotape features two men purported to be bin Laden and his chief surviving deputy, Ayman al-Zawahri. They're shown walking in the mountains.
It's unclear when or where the video was shot. The tape also has voiceovers purportedly of both.
In his audio message, bin Laden does not appear to make any references to recent events that would date the tape, although he does hail five of the Nine-Eleven hijackers.
Al-Zawahri notes the Sept. 11 anniversary and mentions the U.S.-led invasion of Iraq.
Meantime, President Bush is vowing to remember the victims of 9-11, by winning America's war against terrorists he calls "servants of evil.''
Speaking at the FBI Academy in Virginia, he said the best way to prevent a repeat of the terror attacks two years ago is to "stay on the offensive'' at home and abroad.
The president said one way is to give police new weapons against terror suspects. These include subpoenas that don't need a judge's approval, detention without bail and the federal death penalty in cases where it doesn't now apply.
The White House argues these weapons already are in use against drug kingpins and the mafia, and have been approved by the courts.
Bush says in the past two years, America's defenses against terrorism have improved dramatically. But he acknowledged more work is still to be done.
He says the al-Qaida network is "wounded'' but "still dangerous',' and declares, "We cannot afford a moment of complacency.''