The Pentagon says U.S. forces in Afghanistan dropped the military’s largest non-nuclear bomb on an Islamic State target in eastern Afghanistan.

Adam Stump is a Pentagon spokesman. Stump says it was the first-ever combat use of the bomb, known as the GBU-43, which he said contains 11 tons of explosives. The Air Force calls it the Massive Ordnance Air Blast bomb. Based on the acronym, it has been nicknamed the “Mother Of All Bombs.”

Stump says the bomb was dropped on a cave complex believed to be used by ISIL fighters in the Achin district of Nangarhar province, very close to the border with Pakistan.

It was the first time this type of bomb had been used in combat and was dropped from a MC-130 aircraft, Stump said. The bomb was first developed in 2003.

Army Gen. John W. Nicholson, commander of U.S. forces in Afghanistan, said in a written statement that the strike was designed to minimize the risk to Afghan and U.S. forces conducting clearing operations in the Achin area “while maximizing the destruction” of ISIL fighters and facilities. He said IS has been using improvised explosive devices, bunkers and tunnels to strengthen its defenses.

“This is the right munition to reduce these obstacles and maintain the momentum of our offensive against ISIS-K,” he added, using the U.S. military’s acronym for the ISIL affiliate.

Story by the Associated Press and Reuters.