The 10-member panel said in a statement that it had encountered "serious delays" in obtaining information from the Defense Department. It voted to subpoena the Pentagon for documents, tapes and transcripts involving the actions of the North American Aerospace Defense Command, or Norad, on the morning of Sept. 11, as the suicide hijackings were being carried out. The Defense Command is responsible for protecting American airspace.

"In several cases we were assured that all requested records had been produced but we then discovered, through investigation, that these assurances were mistaken," the panel said. "We are especially dismayed by problems in the production of the records of activities of Norad and certain Air Force commands on Sept. 11."

[...]

The White House acknowledged last year, in response to news reports, that one of the daily Oval Office intelligence reports in August 2001, the month before the terror attacks, referred to the possibility that Al Qaeda would hijack passenger planes.

[...]

The subpoena to the Pentagon today was the second that the commission has issued and reflected the panel's growing antagonism with the Bush administration, which had initially opposed the creation of an independent commission to investigate law-enforcement and intelligence failures before the Sept. 11 attacks. The first subpoena was issued last month to the Federal Aviation Administration.