WASHINGTON -- Allied forces have wiped out Libyan air fields and defenses, and no Libyan helicopters are in the air, meaning a no-fly zone is effectively in place, the top U.S. military official said Sunday.

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, said that Western forces have established "24/7" combat air patrols over the rebel stronghold of Benghazi, leaving Muammar al-Qaddafi's air force paralyzed.

"We've had a pretty significant impact in this first 24 hours ... I would say the no-fly zone we were tasked to put in place is now in place," Mullen said on "Fox News Sunday."

But a senior U.S. defense official involved in executing the operation over Libya, a large country roughly the size of Alaska, is limited to Benghazi.

"We do not yet have the capability to enforce a no fly zone throughout the country," said Gen. Carter Ham, the commander of U.S. Africom who's leading the Libya operations for the U.S. "I do anticipate that we will have aircraft over Benghazi 24/7."

Allied aircraft maintaining the no-fly zone include French, Italian, Spanish, Danish, British and American.

Mullen noted that just because Benghazi is protected, that doesn't mean Qaddafi is a goner. The chance exists that Qaddafi could manage to cling to power without a follow-up to the military campaign. 

Qaddafi remaining is "certainly potentially one outcome," Mullen told NBC's "Meet the Press," noting that the U.N.-approved air strikes "are limited and it isn't about seeing him go."

Mullen said the Libyan leader is "going to have to make some choices about his own future" at some point.

Retired Col. Ralph Peters, a Fox News strategic analyst, said the correct military operation would be to go after the problem, which he described as "Qaddafi and his thug sons."

"To end this, somebody, maybe the French because they're the only ones who've got the guts to do it, needs to go after Qaddafi himself," Peters said, asking the point of the military operation. 

"Are we there to drill holes in the sky and do aerobatics?" 

Mullen said that the purpose of the U.N. resolution was to achieve limited objectives so Qaddafi stops killing people. 

"This is not about going after Qaddafi himself or attacking him at this particular point in time," he said.

Peters noted that Qaddafi is ruthless enough to take rebel prisoners, kill them and put those images in front of TV cameras to try to build sentiment against the allied operation. Mullen said he hasn't seen any reports of civilian casualties as a result of the coalition's military operation, but Qaddafi has resorted to using human shields.