by Lester Holt, NBC News anchor

If there is one thing we have all learned since September 11th, 2001, it is that it is extraordinarily difficult to read the tea leaves when it comes to al Qaeda.  When is a message just a message and not a coded attack signal?  When is a threat generic and not a countdown to a specific attack?

Osama bin Laden has surfaced today with yet another audiotape.  In this one he warns Iraq's Sunni Arabs against fighting al Qaeda, and he unleashes threats of holy war against Israel.  As is usual, the experts will analyze the tape to determine its authenticity, when it was recorded (the only date references appear to be September of this year), and if there are any hidden meanings.

Whether by design or coincidence, however, the timing of the tape serves to remind us why the United States is so concerned about the political situation in Pakistan.  Benazir Bhutto was widely admired by policy makers in this country and her death would have been major news no matter what the circumstances.  The fact is, the United States government wanted her back in Pakistan to help stabilize a country that is critical to the war against al Qaeda.  When the question is asked "where is Osama likely hiding?" the answer invariably is "somewhere in the tribal border areas along the Pakistan-Afghanistan border."  A stable, cooperative Pakistani government is necessary for the U.S. to continue the hunt for bin Laden and his associates.  If the death of Benazir Bhutto, possibly at the hands of al Qaeda, didn't remind us of that, this latest tape from bin Laden does.

Tonight on Nightly News, NBC's Ned Colt will report from Pakistan on more violent reaction to the death of Mrs. Bhutto, while here in New York, our Middle East bureau chief Richard Engel, who happens to be home for the holidays, will join me to talk about the significance of this new bin Laden tape.

Also on Nightly News tonight, we'll look at the rising number of police officers being killed in the line of duty.  And it is how many of them are being killed that you may find surprising.  Pat Dawson is working that story for us.

Next time a grocery store clerk asks you "paper or plastic?" you may have a different answer after seeing Kerry Sanders's story on what he found far out in the Pacific Ocean.  Plus, who doesn't admire perfection? Tonight, millions may witness it in a sports broadcast unlike any seen before. We'll tell you what that's all about when we see you tonight for NBC Nightly News.'