U.S. warplanes killed five suspected militants near the Pakistani border, after guerrillas launched an overnight attack on American and Afghan military positions, officials said Wednesday.

The planes were scrambled after insurgents fired 13 rockets at two U.S. bases in the southeastern province of Khost (search) and turned rockets and guns against three border posts late Tuesday, the American military said in a statement.

"Coalition aircraft killed five insurgents," the statement said, adding that U.S. troops also responded with artillery fire from their bases near Khost city. No U.S. or allied forces were hurt, it said.

Taliban-led rebels have maintained a stubborn insurgency along the mountainous border, despite the presence of some 17,000 American troops more than three years after the former ruling militia was ousted for harboring Al Qaeda (search) leader Usama bin Laden.

U.S. commanders insist the insurgents are a waning force, though purported Taliban leaders have threatened a fresh offensive as warmer weather melts snow blocking high passes along the Pakistani border.