The U.S. military on Thursday dropped an MOAB, an approximately 22,000-pound bomb nicknamed the "mother of all bombs," on ISIS forces in Afghanistan — the first time it has been used in combat.

The bomb is touted as one of the largest non-nuclear weapons in the U.S. military's arsenal. Here's what you need to know:

"MOAB" doesn't actually stand for "mother of all bombs"; its formal name is the GBU-43/B massive ordnance air blast.

The U.S. military developed the bomb in 2003, and at the time, "the goal was to put pressure on then-Iraqi dictator Saddam Hussein to cease and desist United Nations violations," according to the Air Force's website.

According to Chris Harmer at the Institute for the Study of War, it has a "blast equivalent of 11 tons of TNT."

The Air Force Research Laboratory Munitions Directorate at Eglin Air Force Base near Valparaiso, Florida, developed the bomb, which uses GPS to navigate to its target, according to the Air Force.

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The bomb is so large that it is carried in the cargo hold of an MC-130 aircraft before it is extracted by parachute from the rear of the plane, Air Force spokeswoman Ann Stefanek said.

"The MOAB then releases from the cradle within 5 seconds of extraction and utilizes global-positioning-satellite-aided guidance and controllable fins to maneuver accurately — to within less than 8 meters — of the intended impact point," she said.

Why was it used in Afghanistan?

The bomb was used against ISIS-Khorasan (ISIS-K) fighters in eastern Afghanistan on Thursday around 7:30 p.m. local time (around 10:30 a.m. ET).

The target was an ISIS-K tunnel complex in the Achin district of the Nangarhar province in Afghanistan.

ISIS-K has been "using IEDs, bunkers and tunnels to thicken their defense" as its "losses have mounted," said Gen. John Nicholson, the commander of U.S. Forces – Afghanistan.

According to Harmer, the use of the bomb could indicate that the U.S. does "not have the depth of resources in Afghanistan to fight effectively against the Taliban/AQD/ISIS" and is "resorting to the MOAB out of desperation."

"The trend over the last 15 years has been to go smaller and more accurate with our weapons," he said.

He said that its use may also be "a signal to [North Korean] leadership that the U.S. has massive conventional weapons that could theoretically be used in a first-strike situation against their nuclear weapons and delivery program."

The MOAB, however, "is not a penetrator weapon and is primarily intended for soft to medium surface targets covering extended areas, targets contained in an environment such as caves or canyons, clearing extensive minefields and for psychological effects," Stefanek said.