Stealth-bombers strike Libyan IS targets on Obama's last day

The fighters "were seen immediately beforehand carrying weapons, wearing tactical vests, carrying mortars and standing in formation," the official said, speaking on condition of anonymity.

The camps were about 45 kilometers (30 miles) southwest of Sirte.

The strike comes one month after the United States officially wrapped up military operations in and around Sirte, where it had conducted nearly 500 strikes to help the GNA expel extremists from the coastal city.

The Pentagon at the time left open the possibility of conducting additional anti-IS attacks if the Libyan unity government asked for help in doing so.

Pentagon spokesman Peter Cook said those targeted included IS fighters who had previously fled Sirte.

"They posed a security threat to Libya, the region and US national interests," Cook said in a statement, noting that the strikes appeared to have been "successful."

The Wednesday evening strike was conducted with the "cooperation" of the Government of National Accord, the defense official added, noting that the move had been authorized by outgoing President Barack Obama.

B-2 stealth bombers, which have a distinctive flying-wing design, conducted the strike with the help of attack drones.

B-2 stealth bombers, which have a distinctive flying-wing design, conducted the strike with the help of attack drones.

The fall of Sirte -- former leader Moammar Gaddafi's hometown located 450 kilometers east of Tripoli -- was a major setback for IS, which has also faced military defeats in Syria and Iraq.

Libya descended into chaos following the NATO-backed ousting of longtime dictator Kadhafi in 2011, with rival administrations emerging and well-armed militias vying for control of its vast oil wealth.

"These strikes will degrade (IS') ability to stage attacks against Libyan forces and civilians working to stabilize Sirte, and demonstrate our resolve in countering the threat posed by (IS) to Libya, the United States and our allies," Cook said.