When the terrorist attacks began on September 11, 2001, numerous U.S. intelligence agencies and facilities that should have been closely following the catastrophic events taking place in the skies over America were unaware that anything was wrong. Because of their particular responsibilities and their advanced capabilities, agencies such as the FBI and the National Security Agency (NSA) should have been among the first to learn the details of the crisis. But, instead, they were apparently in an information blackout, and their knowledge of the attacks was limited to what they could learn from television reports.
The fact that key intelligence agencies and facilities experienced this problem, and all at the same time, suggests that the information blackout may have been intentional–an act of sabotage committed by the perpetrators of the attacks. Such an act could have been intended to render these agencies and facilities useless when their services were urgently needed, thereby helping to ensure that the attacks were successful.
MILITARY OFFICERS UNSUCCESSFULLY SOUGHT INFORMATION ABOUT THE ATTACKS
The lack of awareness of the crisis on September 11 is highlighted in the accounts of two military officers who contacted numerous facilities in their attempts to learn more about the attacks. These officers were Lieutenant Colonel Mark Stuart, an intelligence officer at NORAD’s Northeast Air Defense Sector (NEADS), and Major David McNulty, the senior intelligence officer of the 113th Wing of the District of Columbia Air National Guard at Andrews Air Force Base. 
Stuart and McNulty’s units had crucial roles to play on September 11. NEADS, based in Rome, New York, was responsible for coordinating the U.S. military’s response to the hijackings.  And “air defense around Washington, DC,” according to Knight Ridder, was provided “mainly by fighter planes from Andrews Air Force Base,” which is just 10 miles from the capital.  The DC Air National Guard was in fact known as the “Capital Guardians.”  It was therefore essential that Stuart and McNulty be provided with up-to-the-minute information on the attacks. That, however, did not happen.
NEADS was alerted to the first hijacking–that of American Airlines Flight 11–just before 8:38 a.m. on September 11, when an air traffic controller called to report the incident and request military assistance.  Beginning at around 8:48 a.m., Mark Stuart contacted several facilities to see if they had any information on the hijacking, beyond what he had already learned. These facilities included the FBI’s Strategic Information and Operations Center, the National Military Joint Intelligence Center, and the 1st Air Force headquarters. None of them could provide any additional information. A colleague of Stuart’s checked the SIPRNET–the U.S. military Internet system–for relevant information, but also without success. 
At Andrews Air Force Base, about five minutes or so after he learned that a second plane had hit the World Trade Center (the crash occurred at 9:03 a.m.), McNulty went to his “intel vault” and began seeking relevant information. He too checked the SIPRNET. He called agencies such as the FBI, the CIA, and the NSA. He also called units such as the Air Combat Command Intelligence Squadron and the 609th Air Intelligence Squadron. But he was unable to find out anything more than he had already learned from television reports. 
Other accounts provide further details of the lack of awareness of the catastrophic events within the military and other government agencies. Indeed, the information blackout appears to have been almost universal. One government official commented that the U.S. was “deaf, dumb, and blind” for much of September 11.