WASHINGTON -- "What did they know and when did they know it?" That is a paraphrase of the critical question that dogged Richard Nixon through the dreadful days of Watergate. Now, the same question is being asked again. What did the intelligence community know about the threat of terrorists -- specifically, Osama Bin Laden operatives -- hijacking commercial airplanes for attacks on America before Sept. 11?

It has been reported that U.S. President George W. Bush was briefed more than a month before the Twin Towers attack that the United States was targeted for hijackings. He was informed on the specifics in August, during his vacation on his ranch in Texas, as a part of his daily intelligence briefing. The information was presented as a part of the international intelligence report, which angered the president and caused some serious reviews of the analytic skills of his intelligence support. How did the CIA pick up information on U.S. threats that the FBI missed?

It has also been acknowledged that an FBI agent in Phoenix had urged an investigation of Middle Eastern men enrolled in flight schools and named Osama bin Laden as the controlling sponsor of the threat. The agent's July report suggested that bin Laden's followers could use the schools to train for terror operations. There was never any followup.