BY ROBERT BURNS

AP National Security Writer

WASHINGTON

--Defense Secretary Leon Panetta said Thursday there can be no doubt that terrorists had planned and carried out the attack on the U.S. Consulate in eastern Libya two weeks ago that killed the U.S. ambassador and three other Americans.

Republicans have accused the Obama administration of playing down the possibility of a terrorism link to the Sept. 11 attack, which it initially said was connected to protests over an anti-Islam, Internet video that enraged Muslims worldwide.

"It was a terrorist attack," Panetta said when asked at a Pentagon news conference whether al-Qaida was involved.

He said it remains to be determined by investigators which terrorist group was involved.

Asked how long after the attack it took him to come to the conclusion that it was perpetrated by terrorists, Panetta said, "It took a while," but he was not more specific.

"I think, on the terrorist attack, I mean, as we determined the details of what took place there and how that attack took place, that it became clear that there were terrorists who had planned that attack, and that's when I came to that conclusion," he said.