The assault on the diplomatic office in Benghazi was clearly a planned assault by terrorists, Secretary of Defense Leon Panetta said Thursday, Sept 27, according to CNN.

"As we determined the details of what took place there and how that attack took place, it became clear that there were terrorists who planned that attack," Panetta said.

Panetta's comments are the most definitive to date by an administration official that the Benghazi assault was planned. The U.S. ambassador to the United Nations Susan Rice said on September 16th that the attack "began spontaneously" as a protest against an anti-Muslim film that "spun" from there. Last week, testifying to Congress, the director of the National Counterterrorism Center said, at that point, there was no indication of "significant" plotting.

"What we don't have at this point is specific intelligence that there was a significant advanced planning or coordination for this attack," Matt Olsen said.

Panetta, speaking to reporters at the Pentagon on Thursday, said that determining what terrorists were involved is still a matter to be determined by the investigation.

"It clearly was a group of terrorists who conducted that attack against that facility," Panetta said. "We are not going to let people who deliberately attack and kill our people get away with it."

Asked how long it took for him to make that determination of it being a terror attack, Panetta said "it took a while" once information from the location came back.