officials at the National Security Agency had struck a virtual gold mine of intelligence on the operations of Osama bin Laden. Eavesdropping on a busy phone line at an al Qaeda safehouse in the dust-blown Yemeni capital of Sana, they discovered what proved to be a vital communications hub for the terrorist network. The NSA--America's top-secret electronic spy agency--listened in as al Qaeda's top lieutenants passed messages between bin Laden and operatives worldwide. Analysts suspected that one caller, a man named Khalid, was part of an al Qaeda "operational cadre."
But it was only after the September 11 attacks that authorities realized just how dangerous Khalid was. He turned out to be Khalid al-Mihdar, one of five hijackers who would perish in the attack on the Pentagon. And what no one knew back in early 2000 was that al-Mihdar was in the United States when he called the house in Yemen. The content of some of his conversations, in fact, was reported to the FBI at the time, but neither the FBI nor the NSA investigated much further, officials now say.
The failure to discover al-Mihdar's presence in America--and perhaps stumble upon the hijacking plot--has emerged as one of the most glaring intelligence lapses preceding the 9/11 attacks. It is also now a central focus of the independent 9/11 commission, which plans to address the larger problem in the handoff of information from the NSA to the FBI in an upcoming public hearing. "This was very damaging," says Eleanor Hill, who directed Congress's earlier probe into 9/11. "The intelligence community was not sufficiently focused on the threat to the United States."
Surprisingly, government agencies often did not--or could not--trace the location of all calls made to and from targeted sites, even such high-value ones as the Yemeni house. The failure to follow up on al-Mihdar's calls to Yemen was discussed in oblique and heavily redacted passages in the joint congressional inquiry released last July, which described communications involving "a suspected terrorist facility in the Middle East." U.S. News has learned that the "facility" was the Yemeni safehouse, which authorities describe as one of the most important sources of hard intelligence about al Qaeda before 9/11. The home belonged to Sameer Mohammed Ahmed al-Hada, an al Qaeda facilitator who was also al-Mihdar's brother-in-law. The FBI obtained al-Hada's phone number from a suspect in the twin 1998 bombings of U.S. embassies in Africa.
Over the next three years, sources say, NSA eavesdroppers mined intelligence that helped authorities foil a series of terrorist plots, including planned attacks on the U.S. Embassy in Paris and the U.S. Consulate in Istanbul, along with an attempted airline hijacking in Africa. The home also served as a planning center for the 2000 attack on the USS Cole in Yemen. Al-Hada was killed two years later when a hand grenade he was carrying exploded as he was being chased by Yemeni police.
Waging war. The matter remains shrouded in secrecy, reflecting broader concerns by authorities over revealing details of America's most sensitive intelligence gathering techniques. How the nation's eavesdroppers work and what they listen to are rarely discussed publicly, but the two 9/11 probes have thrown rare light on the inner workings of U.S. intelligence. The failure to detect al-Mihdar's presence in America, for example, reveals another flaw in America's counterterrorism efforts before 9/11: The intelligence community lacked a coordinated program to monitor contact by people in the United States with suspected terrorists overseas. "We were waging a war," says a counterterrorism official, "and nobody knew it, including the troops."
Despite the conventional wisdom that America's intelligence agencies closely monitor international calls to and from the United States, the NSA was exceedingly leery of eavesdropping by accident on what it calls "U.S. persons," who include American citizens and others inside the United States. NSA analysts have had the authority to listen to calls involving U.S. persons if they come into contact with suspected terrorists overseas, but they are not allowed to specifically target Americans. The FBI is also authorized to monitor and trace calls between people in the United States and abroad, but the congressional 9/11 inquiry faulted both agencies for failing to coordinate and plug holes in the coverage. "It was NSA policy to avoid as much as it could any coverage of individuals in the United States," says Hill. "That would have been fine as long as we ensured that the FBI was following up on those areas."
Hill's inquiry found that neither the NSA nor the FBI took full advantage of provisions of the Foreign Intelligence Surveillance Act that would have helped them target such communications--including the targeting of individuals rather than simply individual telephone numbers. Aggressive use of this technique, the inquiry concluded, might have detected al-Mihdar and others earlier. U.S. officials, however, defend their procedures. "If we became aware they were calling for pizza in the United States, we would have called the FBI," insists one of the Bush administration's most senior intelligence officials. "We didn't know."
Still, the episode exposes surprising limitations in America's oft-touted global eavesdropping ability. At the heart of the effort stands the NSA, which controls a massive array of satellites, listening devices, and supercomputers that capture all kinds of foreign electronic signals from telephone calls to missile telemetry. In reality, the NSA is drowning in information, and every day is a constant struggle to process and make sense of the enormous volume of calls it intercepts, intelligence experts say. In many cases, NSA analysts start off with only the identity of a person on one end of the phone call. Sometimes, intercepts pick up only fragments of a conversation.
In the case of the calls to and from the house in Yemen, there were technological limits to what U.S. eavesdroppers could pick up. "Neither the contents of the calls nor the physics of the intercepts allowed us to determine that one end of the calls was in the United States," says the senior intelligence official. It was only after 9/11, prompted by the congressional inquiry, that the FBI delved into toll records and found the U.S. origin of al-Mihdar's calls. In other words, it would have taken initiative on the part of the FBI or other agencies to trace some of the hundreds of phone calls in and out of a target site like the Yemeni house. "NSA did not think it was its job to initiate this research on its own," according to a staff statement by the current 9/11 commission. "It tends to wait to be asked."
The FBI was overwhelmed, as well, and many good leads were simply overlooked as agents tried to cope with the stacks of NSA reports they routinely received. Veteran agents also point out that the Yemen safehouse was one of numerous facilities U.S. intelligence agencies were monitoring. "The amount of data was overwhelming," says Sheila Horan, a former senior official in the FBI's national security division. "When you have a limited number of analysts and agents, you can't possibly cover all those intercepts."
Officials at the FBI and NSA say they have improved their coordination. Changes in national security laws and procedures have given authorities much more latitude to share information and track potential terrorists inside the United States. In particular, Bush administration officials credit the controversial Patriot Act for easing restrictions on how intelligence and law enforcement agencies share information. "Since September 11, the integration and exchange of intelligence on persons who would do Americans harm, whether it be domestically or overseas, has been augmented dramatically," FBI Director Robert Mueller said in a meeting with U.S. News reporters last week.
But looking back, the missed opportunities surrounding one hijacker in particular are sobering. Al-Mihdar's U.S. calls are only one point in a series of events that could have led U.S. officials to the 9/11 conspiracy. A Saudi then in his mid-20s, al-Mihdar first appeared on U.S. radar in late 1999, when the NSA analyzed calls tied to a suspected al Qaeda associate named Khalid. From eavesdropping on the Yemen safehouse, officials had learned of a now infamous meeting in Kuala Lumpur in January 2000, where planning for the 9/11 attack took place. Al-Mihdar was surveilled as he attended the meeting, along with a handful of other al Qaeda operatives, including another future hijacker, Nawaf al-Hazmi. But the CIA failed to get the two men placed on government watch lists, and they entered the United States within days, settling in San Diego. There is one more quirk of fate pointed out by the congressional inquiry. If intelligence on al-Mihdar had made its way from the CIA, NSA, or FBI headquarters to the FBI's San Diego field office, agents say they would have almost certainly started an investigation. They wouldn't have had to look far: One of the field office's longtime informants had had repeated contacts with al-Mihdar.
But, unwatched by U.S. authorities, al-Mihdar left for the Middle East later that year. He returned in 2001, just as America was celebrating its Inde-pendence Day. Two months later, he and four others boarded American Airlines Flight 77 and plunged it into the Pentagon.
