NATO took sole command of air operations in Libya on Thursday as CIA operatives worked the field to connect with rebel fighters who have seen their surge toward Tripoli impeded. The NATO mission -- called Operation Unified Enforcer -- includes an arms embargo, a no-fly zone and "actions to protect civilians and civilian centers," the alliance said Thursday. It follows a U.N. Security Council resolution
allowing member states "to take all necessary measures" -- with the exception of foreign occupation -- to protect civilians under the threat of attack in Libya. Over the weekend, CNN reported that rebels had taken al-Brega, Ras Lanuf and Bin Jawad and reached a town just east of Sirte. But in the last three days, opposition fighters have been pushed back eastward.Rebel forces -- hampered by a lack of organization, training and military know-how when compared to Libyan leader Moammar Gadhafi's troops -- have been demanding an end to Gadhafi's almost 42-year rule in Libya.
But they have been facing sustained attacks and have called for the international community to supply them with better and more powerful equipment.
Saddoun El-Misurati, a spokesman for the Libyan opposition in Misrata, described intense fighting and casualties in the city.
"We managed to get two shipments so far of badly needed medical supplies to the hospitals. But obviously we still need more supplies in dealing with the day-to-day casualties and the situation on the ground," El-Misurati said.
"Our greatest hope will rely mainly on the support of the international coalition forces in the form of change of tactics from the air to target tanks and heavy artillery and also take out groups of sniper positions on buildings and in the city," he said.
Rebel forces have lost Bin Jawad and the key oil town of Ras Lanuf and are backed up to the al-Brega area, opposition member Col. Ahmed Bani said Wednesday. Ajdabiya, which is east of al-Brega, will be prepared as a "defense point" if the withdrawal continues farther east, he said.
Weather conditions prevented a NATO-led coalition from launching more airstrikes in an attempt to weaken Gadhafi's ability to attack civilians, a U.S. representative said Wednesday.
While U.S. and British officials say no decision has been made about whether to arm the opposition, a U.S. intelligence source said the CIA is in the country to increase the "military and political understanding" of the situation.
"Yes, we are gathering intel firsthand and we are in contact with some opposition entities," the source told CNN.
But Robert Baer, a former CIA operative, said on CNN's "AC360" Wednesday night that he's skeptical how effective the agency's action might be.
"I would rather see the Defense Department on the ground, if you have to be there, training," Baer said. "The CIA hates covert action. It rarely works. It worked in Afghanistan, but other times it's almost impossible to do."
Amid the setbacks faced by rebels Wednesday, a significant crack in Gadhafi's armor surfaced when Libyan Foreign Minister Moussa Koussa fled to London and told the government there that he has resigned, the United Kingdom Foreign Office said.
Koussa -- a former head of Libyan intelligence -- was a stalwart defender of the government as recently as a month ago. But in recent weeks, his demeanor visibly changed. At one recent media briefing, he kept his head down as he read a statement and left early.
The Foreign Office called on other members of the regime to follow Koussa's example and "embrace a better future for Libya."
As the battles in Libya continue unfolding, the end game in Libya -- and whether a negotiated exit for Gadhafi would be possible or desirable -- remains uncertain.
The International Criminal Court, at the request of the United Nations Security Council, is investigating alleged "crimes against humanity" by Gadhafi.
Last week, the Chief Prosecutor Luis Moreno-Ocampo said he was certain his investigation would lead to charges against Gadhafi and members of his inner circle. That could complicate any efforts to reach a negotiated exit for the Libyan leader.
Baer said a more drastic approach could be the most effective course.
"I hate to say it, but right now our best chance of ending this conflict is eliminating Gadhafi," he said. "I'm not advocating -- this is just the quickest solution. He is the problem. We're doing these stop-gap measures like bombing. It's stopping a massacre, but on the other hand, we're getting pulled into a quagmire."
CNN's Nic Robertson, Ben Wedeman, Reza Sayah, Dana Bash, Pam Benson, Anderson Cooper, Tim Lister and Zain Verjee contributed to this report
