U.S. intelligence officials will look for clues about Usama bin Laden (search)'s health and whereabouts as they try to authenticate the new videotape of the Al Qaeda (search) leader and his chief surviving deputy.

"This is another reminder that they continue to plot to attack us and to attack freedom," Sean McCormack, a spokesman for the National Security Council (search), said Wednesday.

President Bush, asked about the tape during a tour of forensics labs at the FBI Academy in Quantico, Va., said he had not heard it yet.

In the past, CIA analyses of such messages have taken a day or two to complete.

An intelligence official said the tape was regarded as Al Qaeda propaganda aimed at capitalizing on the Sept. 11 anniversary. Such messages let the network's rank and file know the leadership is still viable, the official said.

Officials also said messages from Al Qaeda leaders sometimes presage an attack.

The Homeland Security Department previously said it did not plan to raise the national terror threat level above its current position at yellow, the third highest of five color-coded levels. The emergence of the tape did not initially appear to alter that course.

It is unclear when or where the video was shot. It contains video of bin Laden and deputy Ayman al-Zawahri (search) walking in the mountains, and voiceovers purportedly of both. The two Al Qaeda leaders look healthy in the picture.

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 Sept. 11 hijackers.

Al-Zawahri notes the Sept. 11 anniversary and mentions the U.S.-led invasion of Iraq, which suggests he spoke sometime after it began in late March.