The death of Osama bin Laden has not eliminated the danger that al-Qaida or an affiliated terrorist group will seek to carry out a strike using a biological or chemical weapon, the recently retired director of the U.S. National Counterterrorism Center said on Thursday.
"We still have pockets of al-Qaida around the world who see this as a key way to fight us," the Associated Press quoted Michael Leiter as saying. "The potential threat from [Yemen-based] al-Qaida in the Arabian Peninsula is very real."
"The most likely ... are simple forms of chemical or biological weapons" instead of a nuclear strike, Leiter said.
He cited the lethal toxin ricin, which is fairly easy to produce, as one bioweapon that might be used. Ricin is derived from commercially available castor beans and can be lethal in very small doses. There is no known antidote.
"Is it going to kill many people? No. Is it going to scare people? Yes," the ex-NCC director said.
Leiter told attendees of the Aspen Security Forum in Colorado that younger generations of violent extremists recognize that causing the deaths of a handful of U.S. citizens can cause the same amount of panic as the much larger-scale plots favored by bin Laden.
"Bin Laden was really prioritizing the big attack," Leiter said. "Some of them may have fantasies about pulling off another 9/11"; however, al-Qaida offshoots understand they can affect U.S. policy and the country as a whole with lower-level strikes.
"Anwar al-Awlaki gets that," Leiter continued, referring to a leader of al-Qaida's Yemen franchise. The Pakistani Taliban, which provided training to the failed 2010 Times Square bomber, also understand that, he said.
Leiter said that the U.S. populace would do well not to blow out of proportion future low-level terrorist attacks, The New York Times reported.
"The American people need to understand that at least the smaller-scale terrorist attacks are with us for the foreseeable future," he said in Colorado.
"The way that we fundamentally defeat that threat, which is very difficult to stop in its entirety, is to maintain a culture of resilience. Although this threat of terrorism is real and there will be tragic events that lead to the deaths of innocent people, it is not, in my view, an existential threat to our society," he said.
Bin Laden's replacement, Ayman al-Zawahiri, is believed to "probably favor smaller targets," ex-CIA Deputy Deputy Director John McLaughlin said at the Aspen event.
The two former officials agreed that al-Qaida's central operation saw its strength reduced following the early May shooting death of bin Laden by U.S. commandos who surprised him at his hideout in Abbottabad, Pakistan, AP reported.
"I think it is now possible ... to actually visualize, to imagine its collapse," McLaughlin said of the organization responsible for plotting the September 11 attacks. He cautioned, though, that Zawahiri and his adherents should not be counted out.
"He's not as charismatic ... but he may be more disciplined," McLaughlin said, noting the longtime Qaida deputy's interest in acquiring and using unconventional weapons.
Leiter appeared skeptical of recent U.S. assessments that the central Qaida leadership in Pakistan was on the brink of elimination, saying those contentions were without "accuracy and precision," The Times reported.
Defense Secretary Leon Panetta earlier this month said that U.S. forces were "within reach of strategically defeating al-Qaida."
While allowing that the al-Qaida operation in Pakistan was "on the ropes," Leiter argued that "the core organization is still there and could launch some attacks" and that "Pakistan remains a huge problem."