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.
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 costs of the operation and whether foreign countries will arm the rebels.
NATO is in the process of taking over control of the airstrikes, which began as a U.S.-led operation. Diplomats said they have given approval for the commander of the NATO operation, Canadian Gen. Charles Bouchard, to announce a handover on Thursday.
Gadhafi's forces have adopted a new tactic in light of the pounding 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, who spoke anonymously in order to discuss sensitive U.S. intelligence on the condition and capabilities of rebel and regime forces. 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.
The official said airstrikes have degraded Gadhafi's forces since they were launched March 19, but the regime forces still outmatch those of the opposition "by far," and few members of Gadhafi's military have defected lately.
The disparity was obvious as government forces pushed back rebels about 100 miles (160 kilometers) in just two days. The rebels had been closing in on the strategic city of Sirte, Gadhafi's hometown and a bastion of support for the longtime leader, but under heavy shelling they retreated from Bin Jawwad on Tuesday and from the oil port of Ras Lanouf on Wednesday.
Gadhafi's forces were shelling Brega, another important oil city east of Ras Lanouf. East of the city in Ajdabiya, where many rebels had regrouped, Col. Abdullah Hadi said he expected the loyalists to enter Brega by Wednesday night.