Washington: The Pentagon says US forces in Afghanistan dropped the military's largest non-nuclear bomb on an Daesh target in Afghanistan.

Adam Stump, a Pentagon spokesman, 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 (MOAB). 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 Daesh, or the so-called ISIS, fighters in the Achin district of Nangarhar province, very close to the border with Pakistan.

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 sources.

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.

Target 

The bomb was aimed at a Daesh cave complex in eastern Afghanistan.

The 22,000-pound bomb, nicknamed the "mother of all bombs," is the largest non-nuclear weapon ever used in combat by the US.

Formally known as the GBU-43 or Massive Ordnance Air Blast (MOAB) bomb, the bomb has been nicknamed the "mother of all bombs" since it was first developed in 2003.

"At 7:32pm local time today, US Forces - Afghanistan conducted a strike on a (Daesh) ISIS-K tunnel complex in Achin district, Nangarhar province, Afghanistan, as part of ongoing efforts to defeat ISIS-K in Afghanistan in 2017," US Forces - Afghanistan said in a statement Thursday.

ISIS-K refers to ISIS-Khorasan, the terror group's affiliate in Afghanistan that mainly operates in the eastern part of the country.

Thursday's use was the first time the MOAB has ever been used in combat.

Maximum destruction

"The strike used a GBU-43 bomb dropped from a US aircraft," the statement continued. "The strike was designed to minimize the risk to Afghan and US Forces conducting clearing operations in the area while maximizing the destruction of ISIS-K fighters and facilities. "

The 22,000-pound bomb was dropped from the rear of an MC-130 aircraft, said Adam Stump, a Pentagon spokesman.

The bomb is so large that it is carried in the cargo hold of the aircraft then rolled out the plane's rear door toward its target.

While the MOAB is the largest bomb ever used in combat, it is not the largest in the US military's arsenal.

That would be the Massive Ordnance Penetrator (MOP), which is 30,000 pounds.

“As ISIS-K's losses have mounted, they are using IEDs, bunkers and tunnels to thicken their defense,” said Gen. John W. Nicholson, commander, US Forces - Afghanistan. “This is the right munition to reduce these obstacles and maintain the momentum of our offensive against ISIS-K.”

Precaution against civilian casualties

Nicholson sought authorisation from higher commanders for the use of the bomb, which was moved to Afghanistan some time ago as planning for the mission was underway.

The military statement added: "US Forces took every precaution to avoid civilian casualties with this strike. US Forces will continue offensive operations until ISIS-K is destroyed in Afghanistan."

Afghan forces and the American troops advising them have engaged in heavy fighting with Daesh forces in Afghanistan over the past year.

An American special operations soldier was killed this past weekend in combat operations against Daesh in Nangarhar Province.

Achin District, which is where the bomb was dropped and is a part of Nangarhar Province, is right on the border with Pakistan.