When al-Qaeda's No. 2 leader, Ayman al-Zawahiri, called off a planned chemical attack on New York's subway system in 2003, he offered a chilling explanation: The plot to unleash poison gas on New Yorkers was being dropped for "something better," Zawahiri said in a message intercepted by U.S. eavesdroppers.
The meaning of Zawahiri's cryptic threat remains unclear more than six years later, but a new report warns that al-Qaeda has not abandoned its goal of attacking the United States with a chemical, biological or even nuclear weapon.
The report, by a former senior CIA official who led the agency's hunt for weapons of mass destruction, portrays al-Qaeda's leaders as determined and patient, willing to wait for years to acquire the kind of weapons that could inflict widespread casualties.
The former official, Rolf Mowatt-Larssen, draws on his knowledge of classified case files to argue that al-Qaeda has been far more sophisticated in its pursuit of weapons of mass destruction than is commonly believed, pursuing parallel paths to acquiring weapons and forging alliances with groups that can offer resources and expertise.
"If Osama bin Laden and his lieutenants had been interested in . . . small-scale attacks, there is little doubt they could have done so now," Mowatt-Larssen writes in a report released Monday by the Harvard Kennedy School of Government's Belfer Center for Science and International Affairs.
Deadly strains of anthrax
The report comes as a panel on weapons of mass destruction appointed by Congress prepares to release a new assessment of the federal government's preparedness for such an attack. The review by the bipartisan Commission on the Prevention of Weapons of Mass Destruction Proliferation and Terrorism is particularly critical of the Obama administration's actions so far in hardening the country's defenses against bioterrorism, according to two former government officials who have seen drafts of the report.
The commission's initial report in December 2008 warned that a terrorist attack using weapons of mass destruction was likely by 2013.
Mowatt-Larssen, a 23-year CIA veteran, led the agency's internal task force on al-Qaeda and weapons of mass destruction after the Sept. 11, 2001, terrorist attacks and later was named director of intelligence and counterintelligence for the Energy Department. His report warns that bin Laden's threat to attack the West with weapons of mass destruction is not "empty rhetoric" but a top strategic goal for an organization that seeks the economic ruin of the United States and its allies to hasten the overthrow of pro-Western governments in the Islamic world.
He cites patterns in al-Qaeda's 15-year pursuit of weapons of mass destruction that reflect a deliberateness and sophistication in assembling the needed expertise and equipment. He describes how Zawahiri hired two scientists -- a Pakistani microbiologist sympathetic to al-Qaeda and a Malaysian army captain trained in the United States -- to work separately on efforts to build a biological weapons lab and acquire deadly strains of anthrax bacteria. Al-Qaeda achieved both goals before September 2001 but apparently had not successfully weaponized the anthrax spores when the U.S.-led invasion of Afghanistan forced the scientists to flee, Mowatt-Larssen said.
"This was far from run-of-the-mill terrorism," he said in an interview. "The program was highly compartmentalized, at the highest level of the organization. It was methodical, and it was professional."
'Not just trying to scare people'
Mowatt-Larssen said he has seen no evidence linking al-Qaeda's program with the anthrax attacks on U.S. politicians and news outlets in 2001. Zawahiri's plan was aimed at mass casualties and "not just trying to scare people with a few letters," he said.
Evidence from al-Qaeda documents and interrogations suggests that terrorists leaders had settled on anthrax as the weapon of choice and believed that the tools for a major biological attack were within their grasp, the former CIA official said. Al-Qaeda remained interested in nuclear weapons as well but understood that the odds of success were much longer.
"They realized they needed a lucky break," Mowatt-Larssen said. "That meant buying or stealing fissile material or acquiring a stolen bomb."
Bush administration officials feared that bin Laden was close to obtaining nuclear weapons in 2003 after U.S. spies picked up a cryptic message by a Saudi affiliate of al-Qaeda referring to plans to obtain three stolen Russian nuclear devices. The intercepts prompted the U.S. and Saudi governments to go on alert and later led to an aggressive Saudi crackdown that resulted in the arrest or killing of dozens of suspected al-Qaeda associates.
After that, terrorists' chatter about a possible nuclear acquisition halted abruptly, but U.S. officials were never certain whether the plot was dismantled or simply pushed deeper underground.
"The crackdown was so successful," Mowatt-Larssen said, "that intelligence about the program basically dried up."