Speaking to reporters, Obama's counter-terrorism advisor John Brennan said, "I think the al Qaeda is looking for those vulnerabilities and facilities and stockpiles in different countries that would allow them to obtain the by-product of nuclear reactors and materials that they can use."
"The terror group was also looking to go after those individuals that might have access to the materials as well as individuals who have the expertise that they need to actually fabricate and improvise nuclear devices," he said.
When asked about the danger of Pakistan's nuclear assets falling into the hands of the al Qaeda, Brennan said, "The ability of a terrorist groups to find weapons or expertise is directly related to the vulnerability of these materials."
"There is evidence of their attempts to do that. I would like to think that we have been able to thwart their success to date," he said when asked if there is any evidence that al Qaeda has actually managed to do that, particularly in Pakistan.
"Terrorist groups and internal criminal organisations will look for the weakest link in a chain and that's why it's so critically important that all countries take their responsibility seriously," he added.