WASHINGTON -- The U.S. commander in Afghanistan who ordered use of the “mother of all bombs” to attack an Islamic State stronghold didn’t need President Donald Trump’s approval, Pentagon officials said Friday.

The officials said Gen. John Nicholson has standing authority to use the bomb, which is officially called the Massive Ordnance Air Blast bomb, or MOAB, the largest non-nuclear bomb ever dropped in combat. The bomb had been in Afghanistan since January.

The officials weren’t authorized to speak publicly on the matter and requested anonymity.

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The bomb’s use has attracted enormous attention, but its aim in Thursday’s attack was relatively mundane by military standards: destroy a tunnel and cave complex used by Islamic State fighters in a remote mountainous area of eastern Afghanistan.

Nicholson had a secondary goal in mind, however, according to an official who spoke on condition of anonymity in order to discuss internal matters. The official said Nicholson wanted to demonstrate to leaders of the Islamic State affiliate in Afghanistan the seriousness of his determination to eliminate the group as a military threat.

The official said use of the weapon had nothing to do with sending a message to any other country, including North Korea.

The Air Force estimates each MOAB costs about $170,000 to build. It hasn’t said how much it cost to develop the bomb or how many of them exist.