Panetta said increased cooperation with Yemen against the al-Qaida affiliate there will not diminish if President Ali Abdullah Saleh leaves power as the U.S. and others have urged.
The Pentagon chief spoke to reporters as he was heading to the Middle East, where he is scheduled to meet with top Israeli and Palestinian leaders. After that he will participate in a meeting of NATO defense ministers in Brussels.
Panetta spoke just days after a CIA drone strike killed Anwar al-Awlaki, the American-Yemeni cleric who served as key inspirational leader within the Yemen-based al-Qaida in the Arabian Peninsula. Killed with him was Samir Khan, a Pakistani-American who produced the group's English-language Web magazine, Inspire. The strike came a few months after a special operations team raid into Pakistan killed Osama bin Laden.
"By virtue of eliminating that leadership, I think it makes it much more difficult for al-Qaida to develop the kinds of plans and operations for conducting large attacks abroad," said Panetta.
He added that he does not know if AQAP's top bombmaker, Ibrahim al-Asiri, was also killed in the strike that targeted al-Awlaki. Officials initially heard al-Asiri may have been killed, but that was later denied by Yemeni authorities.
U.S. counterterrorism officials had considered AQAP a top terror threat because it had been more active in recent plots, including the failed Christmas 2009 attempt to blow up a jetliner headed to Detroit and the effort last year to plant explosives in packages mailed from Yemen to the U.S. and shipped on cargo planes.
The CIA strike came shortly after Saleh returned to Yemen after recovering from severe injuries he received during an attack in Sana'a earlier this year. The impoverished nation has been rocked by more than seven months of protests demanding an end to Saleh's 33-year authoritarian rule. The U.S. has urged Saleh to step down and allow a peaceful government transition.
On Sunday, Panetta said the U.S. has developed a relationship with a number of people in the country's leadership. And he said he believes anyone who takes Saleh's place will continue to be concerned about the terror network there and will cooperate with the U.S. in going after it.