Excerpted from The Black Banners: The Inside Story of 9/11 and the War Against al-Qaeda by Ali H. Soufan with Daniel Freedman. Copyright © 2011 by Ali H. Soufan. With permission of the publisher, W.W. Norton & Company, Inc.

So it is said that if you know your enemies and know yourself, you will win a hundred times in a hundred battles.

-Sun Tzu, The Art of War

"You can't stop the mujahideen," Abu Jandal told me on September 17, 2001. "We will be victorious." We sat across a rectangular table from each other in a nondescript interrogation room with unadorned white walls in a high-level national security prison in Sanaa, the capital of Yemen. The prison was operated by the country's central intelligence agency, the Political Security Organization (PSO), the complex also serving as its headquarters. PSO officials in traditional Yemeni dress were ranged on plastic chairs along one wall, observing the conversation. Abu Jandal-the name means "father of death"-was the most senior al-Qaeda operative in custody; he had served as Osama bin Laden's personal bodyguard and trusted confidant. We got to him through Fahd al-Quso, a Yemeni al-Qaeda operative involved in the October 12, 2000, bombing of the USS Cole. Quso had identified, in a photograph shown to him the previous evening, a man whom we knew to be Marwan al-Shehhi, who was on board United Airlines Flight 175 when it crashed into the south tower of the World Trade Center. Shehhi had once stayed at a safe house in Afghanistan operated by Abu Jandal.

I gave my partner, Naval Criminal Investigative Service (NCIS) special agent Robert McFadden, a bemused look. He raised his eyebrows and smiled at Abu Jandal. Only training and experience enabled Bob and me to smile and appear relaxed, because below the surface we were seething. "You'll find that you have underestimated America," I replied, speaking in Arabic, "but tell me, why do you think you'll be victorious?"

Abu Jandal had been in prison in Yemen for eleven months in the aftermath of the Cole bombing because of his connections to al-Qaeda. Top American security officials were anxiously waiting to see what intelligence we could get from him to help us understand who had destroyed the World Trade Center and part of the Pentagon. We suspected that it was al-Qaeda, but there was as yet no definite proof, and Bob and I had been ordered to identify those responsible for the attacks "by any means necessary"-a command that neither of us had ever received before. Quso's leading us to Abu Jandal was our first indication that al-Qaeda may have been responsible for the attack, but the connection between the two men could have been a coincidence.

Among the thousands of people listed as dead or missing in the World Trade Center were several whom Bob and I knew, including my former boss and mentor at the Federal Bureau of Investigation (FBI), John O'Neill, and a friend and colleague, FBI special agent Lenny Hatton. In Abu Jandal we had someone who took satisfaction in America's pain. Yet a display of anger or the slightest betrayal of the sense of urgency we felt would jeopardize our efforts to get information from him. An interrogation is a mind game in which you have to use your wits and knowledge of the detainee to convince or steer him to cooperate, and essential to this is to show that you are in control. If a suspect thinks that you lack knowledge of what he's talking about or sees that you are flustered, enraged, or pressed for time-these would be signs that he was winning and shouldn't cooperate. We kept the fake smiles plastered on our faces and let Abu Jandal speak.

"You want to know why?" Abu Jandal asked rhetorically, with his usual gusto, as his face broke into one of his trademark broad grins. We had learned that he loved to lecture us-and that was when we could get him to slip up.

"Sure," I said.

"I'll tell you why," he continued. "The hadith says," and he began quoting: "'If you see the black banners coming from Khurasan, join that army, even if you have to crawl over ice; no power will be able to stop them-'"

Abu Jandal paused for a second to catch his breath, but before he could finish the hadith, I continued it for him: "' -and they will finally reach Baitul Maqdis [Jerusalem], where they will erect their flags.'" His grin momentarily left his face, and with surprise in his voice he asked me: "You know the hadith? Do you really work for the FBI?"

"Of course I know that hadith. It's narrated by Abu Hurairah, although it's questionable whether that actually was said by the Prophet," I said, "and I know lots of hadith. As I told you before, the image you have of America and of her people, like me, is all wrong."

Hadith are reported sayings and doings of the Prophet Muhammad, and I was to hear that reputed hadith from many al-Qaeda members I interrogated. It was one of al-Qaeda's favorites.

Khurasan is a term for a historical region spanning northeastern and eastern Iran and parts of Turkmenistan, Uzbekistan, Tajikistan, Afghanistan, and northwestern Pakistan. Because of the hadith, jihadists believe that this is the region from which they will inflict a major defeat against their enemies-in the Islamic version of Armageddon. Bin Laden's 1996 declaration of war against the United States-a main text for al-Qaeda members-ends with the dateline "Friday, August 23, 1996, in the Hindu Kush, Khurasan, Afghanistan." It's not a coincidence that bin Laden made al-Qaeda's flag black; he also regularly cited the hadith and referenced Khurasan when recruiting, motivating, and fund-raising. Al-Qaeda operatives I interrogated were often convinced that, by joining al-Qaeda, they were fulfilling the words of the Prophet.

It is an indication of how imperfectly we know our enemy that to most people in the West, and even among supposed al-Qaeda experts, the image of the black banners means little. Westerners instead focus on al-Qaeda's use, in its propaganda, of its strikes on the United States-the August 1998 East African embassy bombings, the October 2000 attack on the USS Cole, and, of course, 9/11. Such references are obviously important to the organization, but al-Qaeda's use of the black banners is in many ways even more important, because it adds the crucial religious element. If you go into Internet chats rooms where al-Qaeda sympathizers and supporters converse (in Arabic), the black banners are regularly cited.

The hadith has been quoted before in Islamic history: for instance, during the revolution that overthrew the Umayyad Caliphate, the second of the major caliphates set up after the death of the Prophet. The Umayyads were overthrown by the Abbasids in a rebellion that was initiated in Iran, which was then called Khurasan-and the rebels' banners were black. The hadith was also quoted during the fall of Constantinople and the Muslim conquest of Spain.

Many Muslim scholars question the authenticity of the hadith, including the influential cleric Sheikh Salman al-Oadah, jailed for opposing the Saudi government's decision to allow U.S. troops into the country to counter Saddam Hussein's invasion of Kuwait. In his 1996 declaration of jihad, bin Laden quoted Oadah approvingly as being a fellow opponent of troops in the kingdom. Subsequently, however, the sheikh went firmly on record as opposing al-Qaeda, having seen the destruction and death the organization has caused; and he has become a major voice critical of al-Qaeda in the Muslim world. The sheikh, asked about the authenticity of the hadith, said: "The hadith about the army with black banners coming out of Khurasan has two chains of transmission, but both are weak and cannot be authenticated. If a Muslim believes in this hadith, he believes in something false. Anyone who cares about his religion and belief should avoid heading towards falsehood."

There are other hadith that refer to the black banners, including another al-Qaeda favorite: "The black banners will come from the East, led by mighty men, with long hair and long beards; their surnames are taken from the names of their hometowns and their first names are from a Kunya [an alias]."

Abu Jandal quoted it to Bob and me, and I asked him if this was the reason al-Qaeda members let their hair and beards grow long, and change their names so their first reflects an alias and their second, their hometown. He smiled and told me I was right, and told me how it applied to him: while his real name was Nasser Ahmad Nasser al-Bahri, he called himself Abu Jandal al-Jadawi; al-Jadawi means "from Jeddah," which is where he grew up.

Ali al-Bahlul, al-Qaeda's media relations secretary and bin Laden's personal propagandist, whom I interrogated in Guantánamo Bay, Cuba, in 2002, was certain that the coming of al-Qaeda's black banners heralded the apocalypse, which would be followed by the triumph of Islam. "The current war is between the three religions, Christianity, Judaism, and Islam," he told me, "and is the battle of Armageddon predicted in the Old Testament, the New Testament, and the hadith of the Prophet." In Bahlul's mind, because all of this is ordained by God and the holy books, any atrocities and murders of innocent people committed by al-Qaeda are completely justified, and are part of a "heavenly plan." He added, with complete sincerity, "It is a difficult and painful road we are taking, but jihad eases all sorrows."

Asymmetrical organizations like al-Qaeda often develop their own countercultures, with special texts, lore, and codes of conduct, which are usually outside the boundaries of their society's, or religion's, accepted norms. With al-Qaeda this is seen in the leadership's seizing upon questionable hadith and promoting them to the status of most cited and respected of texts. In addition, there is the canonization of events that have become part of the collective consciousness, which in a sense allows believers to create their own religion within Islam. These events include bin Laden's 1996 declaration of war against the United States, his 1998 fatwa, and his 1999 Eid sermon, along with "successful" attacks such as the 1998 East African embassy bombings, the 2000 bombing of the USS Cole, and 9/11.

This lore that they have created for themselves leads al-Qaeda members to believe that they are part of something bigger than they are. Al-Qaeda's aims are well known-to defeat the "crusaders," drive them out of the Arabian Peninsula, and create a worldwide Islamic state-but what binds the operatives together is this narrative that convinces them that they're part of a divine plan.

The counterculture extends not only to scripts and events but to justifications for actions taken that Muslims would normally frown upon. The use of suicide bombing and the killing of innocent people are obvious examples, but extremists through the ages have justified the death of innocents in "war" for a higher cause, and that is not new to al-Qaeda. Indeed, al-Qaeda relies on the interpretations of a thirteenth-century Syrian cleric named Taqi ad-Din ibn Taymiyyah, who justified the killing of bystanders.

What's even more telling is how morally corrupt (in Islamic terms) some al-Qaeda members are. I was shocked when I first discovered that many top operatives did not live according to Islamic principles. Both 9/11 mastermind Khalid Sheikh Mohammed (KSM) and his nephew Ramzi Yousef, the mastermind of the 1993 World Trade Center bombing, were well known in the brothels of the Philippines; Ziad Jarrah, one of the 9/11 hijackers, loved nightclubs and was living with a girlfriend; and Abdul Rahim Hussein Muhammad Abda al-Nashiri, the mastermind of the USS Cole bombing and later head of all al-Qaeda operations in the Arabian Peninsula, was living with a Russian prostitute. Islam also strictly bans the consumption of alcohol, and yet Mohammed Atta, the head of the 9/11 hijackers, was an alcoholic and pounded shots in a bar prior to 9/11, while other hijackers visited strip joints.

It's a tragic irony that these terrorists-who claim to be joining al-Qaeda for the defense of their religion and because they believe in the hadith that say that the war of Armageddon is upon us-disregard the most basic tenets of their religion in the process. They're in violation of the very Islamic law they're fighting to impose.

"Now that you've tested me on a hadith," I said to Abu Jandal, "let me test you on one."

"Sure," he replied eagerly.

"Let me first ask you whether Christians and Jews are allowed in Mecca and Medina."

"Of course not," he replied, shaking his head and giving a condescending smile, "that's a silly question. Everyone knows they're forbidden. Even the Saudi Arabian monarchy, which welcomed infidels into the Arabian Peninsula, wouldn't dare allow them in Mecca and Medina."

"And why aren't they allowed into Mecca and Medina?"

"Because they're holy places."

"Are you familiar with the hadith where the Prophet has dealings with his Jewish neighbor?" I asked.

"Of course."

"Where did those conversations happen?"

"In Medina."

"Did the Prophet commit a sin by allowing a Jew to live next door to him in Medina?"

"Umm," Abu Jandal stuttered, and, after a pause, he replied, "No, the Prophet didn't sin, the Prophet of course never sinned."

"So tell me," I pressed, "if the Prophet said it was okay for a Jew to live next door to him in Medina, how can you say you know more than the Prophet and that Jews and Christians can't live in Medina today?"

Abu Jandal didn't have an immediate response. Thinking for a few moments, he said: "But it is different after the Prophet's death, because on his deathbed, according to the hadith, he said to expel all infidels from the Arabian Peninsula."

"Hold on," I said, "we both know that the Prophet forbade the writing of any hadith during his lifetime, as he wanted the focus to be on the Quran. Hadith were only written about one hundred years later. So you're choosing what the Prophet allegedly said over what he actually did?"

Abu Jandal was at first silent, and then, looking flustered, he said, "Well, there are scholars who determine this."

The king relied on the clerics for domestic support and could not just dismiss their demands. "If what you say is true," he told them, "then we must ban the devil's work, and we will behead those behind it."

"You are a great and wise king," the clerics responded, excited that he was siding with them.

"And so," the king said, "we will hold a public trial tomorrow about this devil box, and it will be brought before me." The king then secretly told the engineers working on the radio to make sure that the Quran was playing at the time of the trial.

The next day, with the clerics present, the king ordered the radio to be brought before him. "Turn this box on," he ordered, and as it was switched on, passages from the Quran were heard. The king, pretending to be confused, turned to the clerics and asked: "Can it be that the devil is saying the Quran? Or is it perhaps true that this is not an evil box?" The clerics conceded that they had been mistaken, and there was no more labeling of the radio as the devil's box.

People ask what is the most important weapon we have against al-Qaeda, and I reply, "Knowledge." What King Abdul Aziz understood is that often the most effective way to beat extremists is to outwit them. As Sun Tzu wrote in The Art of War, when we know our enemy's strengths and weaknesses, and when at the same time we know our capabilities-that's when we are best placed to achieve victory.

This is true in anything from deciding how to interrogate a suspect -whether to torture him or to outwit him to get information-to dealing with rogue states: do we simply resort to force, or do we first try to understand their thought processes and internal divisions and try to manipulate them? It's the difference between acting out of fear and acting out of knowledge.

Our greatest successes against al-Qaeda have come when we understood how they recruited, brainwashed, and operated, and used our knowledge to outwit and defeat them. Our failures have come when we instead let ourselves be guided by ignorance, fear, and brutality. These failures explain why the approximately four hundred terrorists who were members of al-Qaeda on 9/11 have been able to last in a war against the greatest power on earth longer than the combined duration of the First and Second World Wars.

This book tells the story of America's successes and failures in the war against al-Qaeda-from the origins of the organization right through to the death of Osama bin Laden on May 2, 2011 (May 1 in the United States)-with the aim of teaching people the nature of our enemy and how it can be defeated. I was fortunate to work alongside many heroes from the FBI, the Central Intelligence Agency (CIA), the NCIS, and other military agencies, and to work under great FBI leaders, such as Directors Robert Mueller and Louis Freeh, who understood the threat and what needed to be done. The successes in this book are theirs.

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