WASHINGTON –The Pentagon says U.S. forces in Afghanistan dropped the military's largest non-nuclear bomb on an Islamic State target in 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."

U.S. drops 21K LB MOAB, "Mother Of All Bombs" on ISIS-K tunnel camp in Afghanistan. Air Blast bomb largest non-nuclear bomb in US arsenal. pic.twitter.com/Ao080EasnH

— Jamie McIntyre (@jamiejmcintyre) April 13, 2017

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

WATCH: 2003 video shows Dept. of Defense test of 22,000 lb "Mother of All Bombs" that was used in Afghanistan today. https://t.co/SOvEDdiisY pic.twitter.com/fSkGR5NhI1

— ABC News (@ABC) April 13, 2017