U.S. stealth bombers and drones have carried out airstrikes on suspected Islamic State of Iraq and Syria (ISIS) training camps in Libya, and American commanders believe they were successful in destroying the camps.

CBS News national security correspondent David Martin has confirmed with U.S. defense officials that a pair of American B-2 stealth bombers flying non-stop from Whiteman Air Force Base in Missouri carried out the strikes against ISIS training camps Wednesday night.

The B-2s, each capable of carrying as many as 80 precision guided bombs, hit the camps in the desert where U.S. intelligence officials believed ISIS was training scores of fighters to launch terror attacks against targets outside Libya.

Libyan forces allied with the U.N.-backed government fire weapons during a battle with ISIS fighters in Sirte, Libya, July 21, 2016. REUTERS

Martin’s sources said they struck in the middle of the night in Libya, aiming to destroy the camps while the fighters were sleeping.

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“The ISIL terrorists targeted included individuals who fled to the remote desert camps from Sirte in order to reorganize, and they posed a security threat to Libya, the region, and U.S. national interests,” said Pentagon Press Secretary Peter Cook, using an alternate acryonym for ISIS. “While we are still evaluating the results of the strikes, the initial assessment indicates they were successful.”

A U.S. defense official told CBS News “several dozen” militants were believed to have been killed in the strikes, and that no civilians were thought to have been present. The official said militants were seen before the strikes carrying weapons, wearing tactical vests, carrying mortars, and standing in formation at the sites.

Officials said the camps were about 28 miles southwest of the city of Sirte. ISIS has gained a significant foothold in Libya in the chaos that has followed the Western-backed uprising against longtime dictator Muammar Gaddafi, who was killed in 2011.

The strikes were authorized by President Obama, according to U.S. defense officials. The strikes were aimed primarily at ISIS militants who had escaped from Sirte after U.S. strikes virtually obliterated the group in the coastal city last autumn.

The U.S. government first announced airstrikes against ISIS in Libya last summer, in support forces affiliated with the Libyan Government of National Accord (GNA).

State forces and allied militias have engaged in fierce battles with ISIS militants for more than a year, centered around Sirte.