Here are 10 questions about 9/11 that remain unanswered.
1. Did the CIA cover up its advance knowledge of at least two of the 9/11 hijackers?
Richard Clarke, the national counterterrorism czar on 9/11, thinks so. In an interview for an upcoming radio documentary, Clarke claimed that top-level CIA officials deliberately withheld from the White House and the FBI knowledge as early as 2000 that two al Qaeda members - Nawaf al-Hazmi and Khalid al-Mihdhar - were living in San Diego.
The former anti-terror chief said he believes that the CIA kept the info under wraps because it wanted to recruit the two Saudis to serve as double agents within bin Laden's organization. Instead, the two terrorists ended up hijackers on American Flight 77. George Tenet, who was CIA director, claims that Clarke is "reckless and profoundly wrong."
2. How strong is the connection between the 9/11 site cleanup and cancer and other diseases?
Last week, the New York City Fire Department's Dr. David Prezant published research in the prestigious medical journal Lancet showing that male firefighters who responded to 9/11 now have a cancer rate that's 19 percent higher than unexposed co-workers. That comes on top of earlier reports of higher rates of asthma and post-traumatic stress disorder among the responders at Ground Zero.
Indeed, the real questions are a) Why was the Bush administration so lax in issuing warnings about the toxicity of the site in 2001? and b) Why did it take a comedian, Jon Stewart, to shame Congress into funding a health-care bill for the ailing heroes of Ground Zero?
3. Who was really in charge on the morning of 9/11 - Bush or Cheney?
