U.S. officials rarely speak on the record about intelligence intercepts. And in the days following the raid on Osama bin Laden's compound, U.S. officials indicated al Qaeda had gone to great lengths to avoid having its communications intercepted by the United States.  While the precise nature of communication intercepts is rarely discussed, U.S. officials repeatedly have indicated their comfort with sharing the results of those intercepts.  Intelligence officials also say they have picked up "chatter," or widely divergent communications, from extremists that suggest the newly tapped al Qaeda head, Ayman al-Zawahiri, is in some way involved in the current plot.  Meanwhile, heightened security was visible Friday in New York and Washington as intelligence officials worked to pin down information about the potential threat and federal and local law enforcement fanned out across both cities.  A senior U.S. official said the plot was believed to involve three individuals. It is believed to entail a vehicle bomb, but "we cannot rule out other means," the official said.  At least two of the individuals are believed to be American citizens, a U.S. government source said.  U.S. Vice President Joe Biden also weighed in Friday, saying the information was at least in part gleaned from the May raid against bin Laden in Abottabad, Pakistan.  "This is the first ... credible piece of information we've gotten," Biden told NBC's "Today" show. "All hands are on deck."  It is not clear how the bin Laden raid helped authorities connect the dots to the prospect of an anniversary attack, but Biden downplayed the threat of a widely sophisticated plot involving multiple conspirators.
American spy networks have intercepted communications from an al Qaeda operative in Pakistan indicating plans for a terrorist strike in New York or Washington, according to a senior U.S.