U.S. Secretary of Defense Leon Panetta says that when Bashar al-Assad loses his grip on power, he wants the Syrian military to remain in place.

"I think it's important when Assad leaves - and he will leave - to try to preserve stability in that country. And the best way to preserve that kind of stability is to maintain as much of the military, the police, as you can, along with the security forces, and hope that they will transition to a democratic form of government. That's a key," Panetta told CNN's Pentagon Correspondent Barbara Starr in an exclusive interview in Tunis, Tunisia, Monday.

He said the United States shouldn't allow a repeat of the Bush administration's moves in Iraq, where it disbanded the Iraqi military.

"It's very important that we don't make the same mistakes we made in Iraq," he said. "And that, particularly, when it comes things like the chemical sites. They (the Syrian military) do a pretty good job of securing those sites. If they suddenly walked away from that, it would be a disaster to have those chemical weapons fall into the wrong hands - hands of Hezbollah or other extremists in that area."

Panetta had some advice for the Syrian dictator whose nation is in the midst of a deadly civil war. "I'm sure that deep down Assad knows he's in trouble and it's just matter of time before he has to go," Panetta said. "I would say if you want to be able to protect yourself and your family, you better get the hell out now."

Panetta is in Tunisia for the start of a week-long trip to the Middle East and North Africa.

Earlier, on the flight to Africa, Panetta told reporters traveling with him that Syria will be on his agenda on every stop.

"The United States and the international community has made very clear that this is intolerable, and have brought their diplomatic and economic pressure on Syria to stop this kind of violence, to have Assad step down and to transition to a democratic form of government," he said. "The key right now is to continue to bring that pressure on Syria, to provide assistance to the opposition, and to provide whatever kind of humanitarian aid we can to assist the refugees."

Watch Barbara Starr and her exclusive interview with Secretary of Defense Leon Panetta tonight on CNN’s Situation Room with Wolf Blitzer.