After a U.S. airstrike leveled a small compound in Pakistan's lawless tribal regions in January 2006, President Pervez Musharraf and his intelligence officials announced that several senior Al Qaeda operatives had been killed, and that the top prize was an elusive Egyptian who was believed to be a chemical weapons expert.
But current and former U.S. intelligence officials now believe that the Egyptian, Abu Khabab Masri, is alive and well -- and in charge of resurrecting Al Qaeda's program to develop or obtain weapons of mass destruction.
Given the problems with previous U.S. intelligence assessments of weapons of mass destruction, officials are careful not to overstate Al Qaeda's capabilities, and they emphasize that there is much they don't know because of the difficulty in getting information out of the mountainous area of northwest Pakistan where the network has reestablished itself.
But they say Al Qaeda has regenerated at least some of the robust research and development effort that it lost when the U.S. military bombed its Afghanistan headquarters and training camps in late 2001, and they believe it is once again trying to develop or obtain chemical, biological, radiological and even nuclear weapons to use in attacks on the United States and other enemies.
For now, the intelligence officials believe, that effort is largely focused on developing and using cyanide, chlorine and other poisons that are unlikely to cause the kind of mass-casualty attack that is usually associated with weapons of mass destruction.
Intelligence officials say they base their current assessments on anecdotal evidence gleaned from electronic intercepts, information provided by informants and captured Al Qaeda members and the tracking of money flows and militant websites. One international counter-terrorism official said there were indications that some operatives had received immunizations to protect themselves against biological agents.
Abu Khabab, whose real name is Midhat Mursi al-Sayid Umar, is believed to have set up rudimentary labs with at least a handful of aides, and to have provided a stable environment in which scientists and researchers can experiment with chemicals and other compounds, said several former intelligence officials familiar with Al Qaeda's weapons program.
Recent intelligence shows that Abu Khabab, 54, is training Western recruits for chemical attacks in Europe and perhaps the United States, just as he did when he ran the "Khabab Camp" at Al Qaeda's sprawling Darunta training complex in Afghanistan's Tora Bora region before the Sept. 11 attacks, according to one senior U.S. intelligence official, who spoke on condition of anonymity because the CIA's intelligence is classified.
Some experts questioned how far Al Qaeda could get in reconstituting a weapons program in the mountains of Pakistan.
"They are hemmed in in a way that makes it hard to do," said John V. Parachini, a senior analyst on terrorism and weapons of mass destruction at Rand Corp. "It's hard to get the industrial infrastructure together to do these things, and it's hard to get people that have the expertise to fashion these materials into weapons of mass destruction."
Several international counter-terrorism officials concurred with the U.S. intelligence assessment of Al Qaeda's weapons' effort. Raphael Perl, who heads the Action Against Terrorism Unit of the Organization for Security and Cooperation in Europe, said it is widely assumed that Al Qaeda developed chemical weapons years ago, and that if it doesn't have biological capabilities already, "they are certainly not far from it."
Given that Abu Khabab "has the technical knowledge," he said, "it's very, very clear that they are working both in the chemical and biological fields."
Pakistani Information Minister Nisar Memon refused to comment on Abu Khabab and Al Qaeda's weapons program, but security officials from three Pakistani intelligence agencies, speaking on condition of anonymity, confirmed that he is alive.
The senior U.S. intelligence official described Al Qaeda's effort as "a very small, very compartmented program, and not nearly on the scale of what they had going on in Afghanistan, because you don't have the size, the security, you don't have the ease of movement" that the Taliban government provided.
Chris Quillen, a former CIA analyst specializing in Al Qaeda's pursuit of weapons of mass destruction, said the network's program in Pakistan could have made significant progress without authorities knowing about it by operating in small compounds, as it did in Afghanistan.
"I am not saying the programs are great and ready for an attack tomorrow," said Quillen, who left the agency in August 2006 and is now a U.S. government intelligence contractor. "But whatever they lost in the 2001 invasion, they are back to that level at this point."
That is a source of major frustration at the CIA, which a few years back identified at least 40 people that it wanted to kill, capture or question about their suspected involvement in Al Qaeda's weapons program, Quillen and others said. They said at least half of those suspects remain at large.
Abu Khabab's ties to terrorism date to at least the mid-1980s, when he was a prominent member of the Egyptian Islamic Jihad organization led by Ayman Zawahiri, who merged the group with Al Qaeda. Over the years he has trained hundreds of fighters at Al Qaeda's camps on how to use explosives, poisons and rudimentary chemical weapons, according to FBI documents.
Educated in Egypt as a chemical engineer, Abu Khabab has no formal training in biological or nuclear weapons, intelligence officials say. But he has ended up in charge of the weapons program at least in part because some operatives believed to be more knowledgeable about biological and nuclear weapons have been captured or killed.
Abu Khabab was described by several intelligence officials as a cranky, showboating self-promoter as well as one of its top explosives experts. He has had a stormy relationship with the two top Al Qaeda leaders, Osama bin Laden and Zawahiri, and their top command, in part because of his ego and independent streak, those current and former intelligence officials said.
Nevertheless, Zawahiri tapped Abu Khabab in 1999 to head an unconventional weapons program code-named "Al Zabadi," Arabic for fermented milk. Within months, he had made "significant progress," according to Al Qaeda computer files found after the U.S.-led invasion of Afghanistan.
U.S. authorities found materials at the Darunta complex and elsewhere in Afghanistan that showed that Al Qaeda was aggressively pursuing weapons of mass destruction, including nuclear and biological devices, and that it was only a few years away from developing an anthrax weapon. By 2002, Abu Khabab is believed to have fled to Chechnya or the Pankisi Gorge region in Georgia to resume training militants in the use of chemical weapons, before ending up in Pakistan.
In December 2002, Al Qaeda allegedly dispatched a strike team to New York to use a device called a mubtakkar -- or "invention" -- to disperse cyanide gas in subway cars, potentially killing dozens of people, the senior intelligence official said. Several officials said they suspect Abu Khabab played a role in its development.
But Zawahiri scuttled the plot, saying, "We have something better in mind," former CIA Director George Tenet wrote in his 2007 autobiography. Five years later, the U.S. government still does not know what "better" device Zawahiri was referring to, said Quillen and the senior U.S. intelligence official.
Abu Khabab also developed "contact poisons" that could be rubbed on a doorknob or some other common area, and experimented with adding crushed glass to the mixture to help get it into a potential victim's bloodstream, a former WMD case officer at the CIA said.
In recent years, Abu Khabab also began lobbying for more funding to pursue what he claimed would be a successful program to build a nuclear device, according to the former CIA officer and other U.S. officials familiar with the intelligence.
"He has for years told Al Qaeda that he could do it, 'Just give me the money,' " said the former CIA officer, who spoke on the condition of anonymity because of rules preventing former agency officials from discussing details of specific cases. "He's full of crap. He can't. But he can certainly build a good RDD" -- a radiological dispersal device.
Also known as "dirty bombs," radiological dispersal devices have conventional explosives wrapped around radioactive material. When detonated, they can cause some injuries, and potentially widespread contamination and tremendous psychological and economic damage.
In June 2004, the U.S. government had tracked Abu Khabab to Pakistan and issued a $5 million reward for information leading to his capture. The wanted poster said he had been distributing training manuals for making chemical and biological weapons.
In January 2006, U.S. officials caught wind of a purported meeting in Damadola, near the Afghanistan border, that Abu Khabab and other senior Al Qaeda operatives, maybe even Zawahiri, were to attend.
The CIA fired Hellfire missiles from Predator drones at the site, killing as many as 18 people, including at least 13 civilians. Soon after, Musharraf said a son-in-law of Zawahiri and Abu Khabab were among the dead.
Despite Musharraf's claims, the CIA concluded several months later that Abu Khabab was alive, based on evidence from human intelligence and electronic intercepts of conversations in which people talked about him in present tense.
The CIA dispatched additional agents into northwest Pakistan in the summer of 2006, including one specifically responsible for finding Abu Khabab, who officials believe had gone deep into hiding, communicating only by courier.
"I and many other CIA people considered [him] particularly dangerous, given his portfolio for Al Qaeda," said Arthur Keller, one CIA case officer sent to the tribal areas to track Al Qaeda.
"I would have been happy to help him on his way to paradise by any available means," said Keller, who left the CIA later that year, "but the opportunity never arose."
Times staff writer Laura King in Islamabad, Pakistan, contributed to this report.