AJDABIYA, Libya - Moammar Gadhafi's ground forces recaptured a strategic oil town Wednesday and moved within striking distance of another major eastern city, nearly reversing the gains rebels made since international airstrikes began. Rebels pleaded for more help, while a U.S. official said government forces are making themselves harder to target by using civilian "battle wagons" with makeshift armaments instead of tanks.

Western powers kept up the pressure to force Gadhafi out with new airstrikes in other parts of Libya, hints that they may arm the opposition and intense negotiations behind the scenes to find a country to give haven to Libya's leader of more than 40 years.

Also on Wednesday, an American official and former U.S. intelligence officer told The Associated Press that CIA operatives were sent to Libya this month after the agency's station in the capital was forced to close. CIA officers also assisted in rescuing one of two crew members of an F-15E Strike Eagle that crashed, they said. They spoke on condition of anonymity because of the sensitivity of the information.

Even as it advanced militarily, Gadhafi's regime suffered a blow to its inner circle with the apparent defection of Foreign Minister Moussa Koussa. Koussa flew from Tunisia to an airport outside London and announced he was resigning from his post, according to a statement from the British government.

Moussa Ibrahim, a Libyan government spokesman in Tripoli, denied that the foreign minister has defected saying he was in London on a "diplomatic mission."

It was not immediately possible to confirm either statement with Moussa or people close to him.

Gadhafi's justice and interior ministers resigned shortly after the uprising began last month, but Koussa would be the first high-profile resignation since the international air campaign began.

Airstrikes have neutralized Gadhafi's air force and pounded his army, but his ground forces remain far better armed, trained and organized than the opposition.

The shift in momentum back to the government's side is hardening a U.S. view that the poorly equipped opposition is probably incapable of prevailing without decisive Western intervention - either an all-out U.S.-led military assault on regime forces or a decision to arm the rebels.

In Washington, congressional Republicans and Democrats peppered senior administration officials with questions about how long the U.S. will be involved in Libya, the operation's costs and whether foreign countries will arm the rebels.

NATO is taking over control of the airstrikes, which began as a U.S.-led operation. Diplomats said they have given approval for the NATO operation's commander, Canadian Gen. Charles Bouchard, to announce a handover today.

Intelligence experts said the CIA operatives that were sent to Libya would have made contact with the opposition and assessed the rebel forces' strength and needs if Obama decided to arm them.

The New York Times first reported that the CIA had sent in operatives and that British operatives were directing airstrikes.

Gadhafi's forces have adopted a new tactic in light of the pounding that airstrikes have given their tanks and armored vehicles, a senior U.S. intelligence official said. They've left some of those weapons behind in favor of a "gaggle" of "battle wagons": minivans, sedans and SUVs fitted with weapons, said the official.

Rebel fighters also said Gadhafi's troops were increasingly using civilian vehicles in battle.

The change not only makes it harder to distinguish Gadhafi's forces from the rebels, it also requires less logistical support, the official said.