First on CNN: US drops largest non-nuclear bomb in Afghanistan

Washington (CNN) - The US military has dropped an enormous bomb in Afghanistan, according to four US military officials with direct knowledge of the mission.

A GBU-43/B Massive Ordnance Air Blast Bomb (MOAB), nicknamed the "mother of all bombs," was dropped at 7:32 pm local time Thursday, the sources said. A MOAB is a 21,600-pound, GPS-guided munition that is America's most powerful non-nuclear bomb.

The bomb was dropped by an MC-130 aircraft, stationed in Afghanistan and operated by Air Force Special Operations Command, Pentagon spokesman Adam Stump told CNN.

Officials said the target was an ISIS cave and tunnel complex and personnel in the Achin district of the Nangarhar province.

"The United States takes the fight against ISIS very seriously and in order to defeat the group we must deny them operational space, which we did," White House press secretary Sean Spicer said later Thursday. The strike "targeted a system of tunnels and cave that ISIS fighters use to move around freely."

The military is currently assessing the damage. Gen. John Nicholson, commander of US forces in Afghanistan, signed off on the use of the bomb, according to the sources. The authority to deploy the weapon was granted to Nicholson by the commander of US Central Command, Gen. Joseph Votel, Stump said.

This is the first time a MOAB has been used in the battlefield, according to the US officials. This munition was developed during the Iraq War. - More

First on CNN: US drops largest non-nuclear bomb in Afghanistan ...