Panetta spoke to reporters aboard a military plane on his way from Latin America, where he visited Colombia, Brazil and Chile to bolster bilateral military cooperation and regional security ties.

“Having been involved in the operations, even before we did bin Laden, it’s clear that there is no kind of silver bullet here to suddenly being able to destroy al Qaeda, and that includes even going after bin Laden,” he said.

“But the way this works is that the more successful we are at taking down those who represent their spiritual and ideological leadership, the greater our ability to weaken their threat to this country and to other countries.”

The al Qaeda founder and 9/11 mastermind was killed on May 2 last year in a secret US Navy SEAL operation in a walled-off compound in the Pakistani garrison town of Abbottabad, north of the Pakistani capital.

His death further weakened al Qaeda, and it was unlikely the terror group could stage another strike on the scale of the attacks of September 11, 2001, a counterterrorism official told reporters at the Pentagon on Friday.

Panetta said he was certain that America was safer as a result of the bin Laden operation.

“When you combine that with the other operations that have taken place, that have gone after al Qaeda leadership, I think it really has weakened al Qaeda as an organization and certainly it has prevented them from having the command-and-control capability to be able to put together an attack similar to 9/11,” the defense secretary pointed out.

He cautioned, however, that this did not mean that there was no longer a terrorism threat.

“It doesn’t mean that we somehow don’t have the responsibility to keep going after them wherever they are,” Panetta said.

But he insisted that, given the successes of the past, America was now more secure. AFP