At roughly 7pm local time on Thursday, the United States military used its GBU-43/B Massive Ordnance Air Blast Bomb (MOAB), nicknamed “the mother of all bombs,” for the first time in combat. The US Air Force used it in Afghanistan to target Islamic State tunnels and personnel. The 21,000-pound (9,525 kg) bomb was dropped in the Achin district of the Nangarhar province in eastern Afghanistan.

The Pentagon confirmed the use of the MOAB, and is currently assessing damage. General John Nicholson, commander of US forces in Afghanistan, signed off on its use, CNN reported. Authority was also sought from General Joseph Votel, commander of US Central Command (CENTCOM). The Air Force “took every precaution to avoid civilian casualties,” CENTCOM added.

CENTCOM after U.S. drops GBU-43 bomb on ISIS targets in Afghanistan: U.S. "will continue offensive operations until ISIS-K is destroyed." pic.twitter.com/qyrNXhpQbu — ABC News (@ABC) April 13, 2017

“The strike was designed to minimize the risk to Afghan and U.S. Forces conducting clearing operations in the area while maximizing the destruction of ISIS-K fighters and facilities,” CENTCOM said in a statement, referring to Islamic State Khorasan, the branch of Islamic State (IS, formerly ISIS/ISIL) in Afghanistan, Pakistan and Uzbekistan.

The Air Force developed the MOAB in 2003 during the Iraq war, but it had never been used in combat until Thursday. The Pentagon produced 15 MOABs at a cost of $16 million per unit, according to military information website Deagel. The use of the bomb comes as the US involvement in Afghanistan heads into its 16th year in the fall, and days after Staff Sergeant Mark De Alencar, a US Special Forces operator, was killed in the same region.

"The soldier was mortally wounded late Saturday during an operation in Nangarhar Province," US Navy Captain Bill Salvin tweeted.

The MOAB was designed to target large below-ground areas. It would have “feel like a nuclear weapon to anyone near the area," Lieutenant Colonel Rick Francona (ret.) told CNN. The GPS-guided munition would have already been in country before it was dropped out of an MC-130 aircraft, operated by Air Force Special Operations Command, military sources told CNN’s Barbara Starr.

Nicholson described the MOAB as “the right munition to reduce” the improvised explosive devices (IEDs), bunkers and tunnels IS is using to “thicken their defense.” The bomb will also “maintain the momentum of our offensive against ISIS-K,” he said.

President Donald Trump told reporters that he's given the military "total authorization," and "that's why they've been so successful lately." When asked if the use of the MOAB in Afghanistan might send a message to North Korea amid increased tensions with the isolated country, Trump replied: "I don't know if it sends a message, I don't care if it does or not."

A peace conference on Afghanistan is scheduled to begin on Friday in Moscow, involving the Afghan government and representatives of twelve other nations. The US was invited to the conference, but reportedly declined to participate.

Below is a video of the bomb in action.