A senior Central Intelligence Agency officer has resigned so he can speak openly about what he sees as the government's failure to understand the threat from the al-Qaida terrorist network.

Michael Scheuer, the former chief of the CIA's Osama bin Laden unit, said he believes there has not been adequate national debate over the nature of the threat posed by bin Laden and the forces he leads and inspires.

The CIA allowed Mr. Scheuer to publish his book "Imperial Hubris" anonymously and to conduct media interviews under the name "Mike."

But he became a critic of the U.S.-led war in Iraq, saying it has inflamed anti-American sentiment among Muslims, and his name eventually became known.  He is also critical of how CIA resources are being used to go after al-Qaida.

The CIA has declined to comment.

Some information for this report provided by AP.