Watch: Spicer holds White House briefing after US bombs Afghanistan

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White House Press Secretary Sean Spicer held his press briefing after U.S. forces dropped the largest non-nuclear bomb on an ISIS tunnel complex in Afghanistan on Thursday.

Spicer said that ISIS fighters use the caves to "move around freely." He explained that in order to defeat the terrorist group, the U.S. must deny it operational space.

The Pentagon said 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."

Spicer said that the military did what it could to avoid civilian casualties and collateral damage.

ISIS has been using IEDs, bunkers and tunnels as losses increased, Gen. John W. Nicholson, commander of U.S. forces in Afghanistan, explained.

"This is the right munition to reduce these obstacles and maintain the momentum of our offensive against ISIS-K," Nicholson said in a statement.

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