(AP) - U.S.-led military action in Libya hasbolstered rebels fighting Moammar Gadhafi's forces, but theinternational operation could continue for months, the Obamaadministration says.

Ahead of President Barack Obama's national address Monday toexplain his decision to act against the Libyan leader, DefenseSecretary Robert Gates and Secretary of State Hillary RodhamClinton said in appearances on the Sunday talk shows that theintervention had effectively rendered Gadhafi's forces defenselessagainst air attacks and created the conditions for oppositionadvances westward.

In interviews taped Saturday, Gates and Clinton also defendedthe narrowly defined U.N. mandate to prevent atrocities againstLibyan civilians and said the U.S. had largely accomplished itsgoals.

"We have taken out his armor," Gates said, adding that theU.S. soon would relinquish its leading role in enforcing a no-flyzone and striking pro-Gadhafi ground targets intent on violence.

Clinton said "we're beginning to see, because of the good workof the coalition, his troops begin to turn back toward the west -and to see the opposition begin to reclaim the ground they hadlost."

Libyan rebels reclaimed an important oil town and kept pushedwestward Sunday toward the capital, Tripoli. Brega, a main oilexport terminal in eastern Libya, fell after a skirmish lateSaturday. Rebel forces also seized the tiny desert town of Al-Egilaon their way to the massive oil refining complex of Ras Lanouf.

U.S.-led airstrikes allowed anti-government forces to recapturethe key eastern city of Ajdabiya.