As US bombs strafed Afghan-istan one night in December 2001, the incessant blasts killed, among others, Mohammed Atef, Al Qaeda's No. 3 in charge of military operations. The next March, a US-Pakistani sting netted operations chief Abu Zubaydah, whom US intelligence officials decreed the next No. 3, tucked away in one of Pakistan's sprawling metropolises. A year later, a slumbering Khalid Sheikh Mohammed - the third No. 3 - was abducted in a dawn raid. More recently, the last known No. 3, spiritual counselor and operations coordinator Saif Al-Adel, was put under house arrest in Iran.
The story of Al Qaeda's multiple No. 3s is a story of how far the US has come in infiltrating and subduing Osama bin Laden's worldwide terror network in the two years since 9/11 - but also of the huge tasks that remain. These four men are part of the US success story in the war on terror: They're among the two-thirds of Al Qaeda leadership that US officials say have been captured or killed as a result of one of the most concerted worldwide dragnets in US history - and intelligence garnered from some of those detained.
Yet they're also the face of American setbacks, an Al Qaeda that bounces back like mercury dropped on a laboratory floor. The result, say intelligence officials, is that two years after the cataclysmic attacks on US soil, Al Qaeda is a weaker, more diffuse organization, but one that can still mount substantial attacks - in the US and abroad.
Indeed, the vanquishing of four No. 3s shows how constantly leaders must move and change tactics. But it also sheds light on Al Qaeda's organization and deployment - and, especially, on the depth of its following.
"Al Qaeda had a much deeper bench than we'd imagined before 9/11, and it clearly had a corporate succession plan," says Bruce Hoffman, an expert on terror at the RAND Corp. in Washington. "It's now clear that Al Qaeda's strength was not just its hard core, which existed before 9/11, but the layers below - and those other groups affiliated with Al Qaeda."
New insights have led government officials to say Al Qaeda is as dangerous, or more so, than it was before 9/11. And they continue to say the war on terror won't be won in months, but over several years.
"Despite these strikes against the leadership of Al Qaeda, it remains a potent, highly capable, and extremely dangerous terrorist network - the No. 1 terrorist threat to the US today," the FBI's chief counterterrorism official, Larry Mefford, told a Congressional committee in late June. "We remain concerned about Al Qaeda's ability to mount simultaneous and large-scale terrorist attacks."
To be sure, there have been tremendous successes in the effort to eradicate Al Qaeda. The Taliban regime was swiftly swept aside in Afghanistan, depriving Al Qaeda of its operational base. Since then, some 3,000 members have been detained. Treasury Department officials have blocked $140 million in Al Qaeda funds.
One measurement of gains, of course, is the prevention of additional "spectaculars," as government officials call strikes on the homeland, like those of 9/11. That's no small feat. But it's difficult, most experts and government officials say, to set other benchmarks because there isn't a firm number of followers against which to measure thinning of the ranks.
"I think we have made a real difference in the subset of Al Qaeda that conducts terrorism," says a senior intelligence officer. "It would be hard for me to imagine we haven't made a dent. How much of a dent would be hard to guess because we don't have a baseline, a measure."
Most officials and experts now believe that Osama bin Laden acts as CEO over a top-down and bottom-up organization. The corporate structure is not clear. It's known only that Mr. bin Laden has a close-knit, compartmentalized group charged with heading military operations, recruitment, training, religious education, and other leadership functions. For instance, Mr. Mohammed, caught in Karachi, was allegedly responsible for 9/11 planning and logistics. He headed what officials call one "franchise." The problem is, they don't know how many other franchises are out there.
They do know that some 100,000 fighters trained at Al Qaeda camps during the 1980s and '90s. Most returned to their homes in more than 15 Arab countries; many now belong to local terrorist groups, or insurgencies, inspired and funded by bin Laden. Jemaah Islamiyah in Indonesia is an example. Members of this group carried out several bombings, including the October 2002 bombing in Bali, in which 202 people were killed.
The FBI's Mr. Mefford told the Congressional committee that the FBI knows of domestic support cells and has "ongoing operations directed against suspected Al Qaeda members and their affiliates in about 40 states." In fact, the Department of Homeland Security alerted communi-ties last week that Al Qaeda operatives may use new tactics in the US - suicide car bombings, disguising themselves as women, or hijacking planes from Canada or Mexico into the US. And the FBI put out an alert for four suspected terrorists who may be hiding and scheming in the US.
But in addition to domestic threats, US interests abroad - especially in Asia and the Middle East - have long been, and remain, key sites for intrigue. With the chaos in Iraq, the time may be ripe for attacks and recruitment.
"I think you have the World Series of jihad going on now in Iraq," the senior intelligence officer says. "It's an unexpected gift for Al Qaeda and bin Laden. He's always said that Al Qaeda can't wage this global jihad by itself. He's been trying to instigate, inspire Muslims - and his attacks on the US over the years have done that." He says bin Laden counts on US policies - support for Israel, a quest for cheap oil, and cracking down on powerful Muslim nations - to inspire Muslims worldwide.
The Pew Global Attitudes Project, a survey of thousands in 44 nations released in June, showed that a significant number of those in the Muslim world trust bin Laden to "do the right thing regarding world affairs." Some 71 percent of Palestinians felt this way, as did solid majorities in Indonesia and Jordan - considered a close US ally - and nearly half those in Morocco and Pakistan.
Yet the US has leaned on Muslim allies to fight Al Qaeda, especially in Yemen and Saudi Arabia, home to 15 of the 9/11 hijackers and the "epicen-ter" of Al Qaeda funding, according to a US Treasury Department official in June.
Saudi Arabia has indeed made inroads - particularly since the May 12 attacks in Riyadh. The Saudis have captured or killed hundreds of jihadists and changed their financial system to keep funds from Al Qaeda. Yemen, the site of two attacks in the past 2 1/2 years, including the strike on the USS Cole, has also proved helpful, aiding US intelligence and confronting its support for Al Qaeda - including "re-education" of its young jihadists.
But the very existence of these endemic support systems explains, also, why the war on terrorism is so long-term. "Much remains to be done," Treasury Department general counsel David Aufhauser told a Congressional committee in June. "We will continue to use every tool of diplomacy, regulation, law enforcement, and intelligence to attack terrorist financing."
9/01 - Al Qaeda members crash two hijacked planes into the World Trade Center towers and one into the Pentagon (photos at left), killing about 2,900. A fourth crashes into a Pennsylvania field.
10/01 - Opening of a US-led campaign to topple Afghanistan's ruling Taliban, who are believed to harbor Al Qaeda members including leader OSAMA BIN LADEN.
12/01 - US bombers attack the mountainous region of Tora Bora in Afghanistan. The US believes it has Mr. bin Laden and his top commanders surrounded, but they elude an intensive air campaign.
-MOHAMMED ATEF, military planner for Al Qaeda and suspected mastermind of the 1998 bombings of US embassies in Kenya and Tanzania, is killed in Afghanistan by an aerial bombardment.
- The US charges ZACARIAS MOUSSAOUI in connection with the Sept. 11 attacks. Mr. Moussaoui had trained at a US flight school in February.
1/02 - Alleged Taliban and Al Qaeda prisoners from Afghanistan are taken to the US Naval base at Guantánamo Bay, Cuba. They are designated "illegal combatants" and so are not protected as prisoners of war under the Geneva Convention.
3/02 - ABU ZUBAYDAH, believed to be Al Qaeda's No. 3 after Mohammed Atef's death, is captured in a US-Pakistan sting and handed over to the US.
6/02 - Morocco arrests MOHAMMED HAYDAR AL-HAILI, alleged to be a top Al Qaeda recruiter.
7/02 - Congress votes to create a new Department of Homeland Security.
8/02 - Moroccan MOUNIR AL-MOTASSADEQ, on trial in Germany, is the first person convicted as a conspirator in the Sept. 11 attacks.
9/02 - RAMZI BINALSHIBH, believed to be a key Sept. 11 planner, is arrested in Pakistan.
10/02 - A bomb in a Bali nightclub kills 202. Suspicions center on Al Qaeda.
11/02 - In Yemen, US missiles destroy a car believed to be carrying six members of Al Qaeda, including ALI QAED SENYAN AL-HARITHI, a suspect in the October 2000 attack on the USS Cole. Separately, the US arrests a key planner in the Cole attack, ABD AL-RAHIM AL-NASHIRI.
1/03 - Muhammad Ali Hassan al-Muyad, a suspected Al Qaeda recruiter and financier, is caught in a CIA-FBI sting spanning Yemen and Germany. The US is now trying to extradite and prosecute him for funding Al Qaeda and Hamas.
3/03 - KHALID SHEIKH MOHAMMED, now considered No. 3 in Al Qaeda and an operational architect of Sept. 11, is arrested in Pakistan.
5/03 - Saudi Arabia's capital is rocked by the bombing of a housing compound for foreign nationals. Thirty-five people, including 12 Americans, are killed in the suicide car bombing, which bears hallmarks of Al Qaeda.
7/03 - Iran is believed to have taken some of Al Qaeda's top tier into custody, including bin Laden's son SAAD BIN LADEN; Al Qaeda spokesman SULAIMAN ABU GHAITH; and SAIF AL-ADEL, the latest to take the group's No. 3 post.