WASHINGTON —  Government officials believe the tape of Usama bin Laden (search) aired Friday was made recently and are trying to determine whether its release now may be a signal of an impending attack.

Intelligence experts have determined the tape "lacks what we assess to be an explicit threat and reiterates well-worn themes," said one U.S. official, who spoke on condition of anonymity.

Yet many U.S. intelligence analysts and law enforcement officials have been warning that a message from bin Laden might signal an attack. A government official, who has been briefed on current threat intelligence, said that all the attack scenarios considered by government analysts include such a message.

"The one piece they were waiting for is some kind of bin Laden videotape. And now they've got it," the official said, speaking on condition of anonymity. "This has everybody on edge."

The administration, however, did not plan to raise the nation's threat level for now, White House spokesman Scott McClellan (search) said. Most of the country has been at yellow alert, the middle of the government's five-point warning scale, for the bulk of the year.

All officials cautioned that the tape was still being studied.

Analysts have been able to determine with a "high degree of confidence" that the voice and image on the 18-minute tape — parts of it aired by Al-Jazeera — are of bin Laden, the U.S. official said.

Among indications that the video was made recently, the U.S. official noted that bin Laden mentions that it's been three years since Sept. 11, 2001, and that U.S. deaths in Iraq have reached 1,000.

That milestone was reached in early September.

At the beginning of the video, there is also text that attributes the video to al-Sahab for Media Production, Al Qaeda's media committee, and says it was made 10 Ramadan (search), or last Sunday. However, experts analyzing the tape cannot confirm that precise dating, the U.S. official said.

This video is of further interest to analysts because it has English subtitles — a first for bin Laden. "We are still really early in our analysis, and we are proceeding with caution," the U.S. official said.

Nothing about bin Laden's health or appearance has jumped out yet, the U.S. official added. However, the official noted, if you compare it to the last known time bin Laden could be seen speaking on video — in December 2001 — he looks a little thinner.

The tape sparked a flurry of U.S. government meetings Friday evening as officials assessed the tape and what action to take.

A U.S. senior law enforcement official, also speaking on condition of anonymity, said the tape was being scrutinized by a special FBI task force formed to disrupt a potential attack timed to coincide with the U.S. election campaign.

The FBI and other counterterrorism agencies are especially interested in finding any hidden messages or other clues that might signal an Al Qaeda attack, the official said.

The FBI also is comparing the tape to one that was aired by ABC Thursday evening in which an unidentified, disguised man claiming to be an American threatens more attacks against the United States.

Before the bin Laden tape was aired, the State Department urged the government of Qatar not to broadcast it, a senior State Department official said. Qatar helped al-Jazeera launch in 1996 with a $150 million loan, but the news network has since claimed full independence.

The U.S. reasoning was that the satellite television network should not give a platform to someone who runs terrorist operations and promotes terrorist activities, said the official, who spoke on condition of anonymity.

Al-Jazeera defended its decision to air the tape, saying no one could question its news value. Spokesman Jihad Ali Ballout said the station received the tape Friday but would not say how.

Bruce Hoffman, a terrorism expert at the RAND think tank, said the timing of the tape is "exquisite" because it allows bin Laden to elbow himself into the limelight of the presidential election.

Hoffman, however, doesn't think the message is intended to sway the outcome, but rather U.S. policy. "He is the sworn enemy of whoever is elected president," Hoffman said.