JANUARY 20, 2006 - Posted at 7:49 a.m. CST
WASHINGTON (AP) - The U.S. isn't raising the terror threat level, but a new audiotape threat from Osama bin Laden is provoking a reponse in other fronts.
An FBI official says the Bureau is asking intelligence units at 56 field offices to take a second look at cases and investigative leads.
Los Angeles police say they're beefing up patrols of officers and bomb-sniffing dogs at the airports.
The Department of Homeland Security says it's found no "corroborating information" to suggest an imminent attack. But spokeswoman Michelle Petrovich says it knows "al-Qaida remains committed to striking the homeland."
Intelligence expert Ben Venzke says he believes bin Laden's first public communication in more than a year could be related to a warning cycle or an actual attack plan by al-Qaida.