Retired four-star Gen. Jack Keane joined Martha MacCallum on "The First 100 Days" tonight to react to the U.S. military's use of "the mother of all bombs" in Afghanistan

He said the bombing was less about sending a message to other U.S. adversaries and more about taking out ISIS targets, which he said this bomb was particularly well-suited for.

The MOAB (Massive Ordnance Air Blast) - also known as "the mother of all bombs" - was deployed in Nangarhar Province on Thursday, targeting an ISIS tunnel complex.

Keane explained that the 21,000-pound ordnance not only creates a massive blast, but it also produces an "incendiary fuel" that permeates below-ground bunkers and tunnels.

"This is a nasty weapon," Keane said. "The nature of the target was actually driving this more than anything else."

He said that the commander who ordered this strike has "tunnel-vision" for destroying ISIS, as opposed to delivering a message to Russia, China, North Korea, Iran or anyone else.

"He's focusing on killing [ISIS], and he's selected the best weapon in his arsenal."

Watch more above.

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