A week and a half ago, the most powerful conventional bomb in the U.S. arsenal rolled out the back of a U.S. Air Force MC-130 special operations aircraft lumbering in the skies over Afghanistan.

Marking its first-ever deployment in combat, the 21,600-pound GBU-43 Massive Ordnance Air Blast (MOAB) — nicknamed “mother of all bombs” — dropped from the cargo plane to a specific location in the Achin district in Nangarhar province in the eastern part of the country, where militants affiliated with the Islamic State of Iraq and Syria‘s branch Khorasan, or ISIS-K, had amassed in a tunnel complex.

The strike killed at least 94 militants, a U.S. military official said, and reportedly two civilians, an Afghan parliamentarian told The Guardian. The bombing made headlines around the world as an example of American military might. Observers said it also sent a message to potential adversaries, such as North Korea, that U.S. commanders under President Donald Trump are more willing to deploy deadlier weapons.

Yet questions remain over the bomb’s future use and cost. Experts have questioned MOAB’s estimated price tag of $170,000. In terms of explosive yield, a B-52 bomb load can pack the same punch, if not more. And the Air Force has a limited supply of the munitions, which were built in-house with various pieces and parts shortly after the war in Afghanistan began in 2001.

“It’s basically a frankenbomb,” one official said.

Most Powerful, Not Biggest

To be clear, the Air Force‘s Massive Ordnance Air Blast, or MOAB, bomb is not the same as its GBU-57A/B Massive Ordnance Penetrator, or MOP.

Read more of this story at Military.com.