Transcript for MOAB fallout from US Afghanistan strike

Next to the fallout from the U.S. Strike in Afghanistan. The largest conventional weapon the U.S. Has ever deployed in combat, targeting ISIS. And now assessing the damage, and searching for information. Tonight, the questions, what did the strike accomplish, and at what cost? Terry Moran in London tonight. Reporter: The Pentagon video shows the immense destructive power of this weapon, devastating an entire mountain valley. The boiling plume of smoke quickly turning into a mushroom cloud, rising over the massive blast area. Take another look. The quiet valley, then you can see the bomb falling there, guided by internal gps right to the target. The tremendous explosion. And you can actually see the blast wave radiating across the landscape. Afghan villagers miles away said they could feel the Earth shake when it detonated. Reporter: "My house was shaking after the blast," this man said. "The whole area was burning on fire." "We are very happy" with the bomb, said another local resident. "We ask the kabul government to use even stronger weapons against them." The bomb, officially a massive ordnance air blast, is 30 feet long, weighs 20,000-plus pounds, and is dropped from a cargo plane, and delivers in a single explosion the equivalent of 11 tons of tnt. The most powerful weapon the U.S. Has used since the Hiroshima atomic bomb. Afghan officials initially saying 36 ISIS fighters were killed and no civilians. If you look at that terrain, if U.S. Forces would've had to have climbed up those steep hills, that high altitude, and had to have dug those ISIS fighters out of those caves, it would've been a great danger. And so using this weapon here and now inevitably saved American lives. Reporter: Out on the campaign trail, then-candidate Donald Trump made point-blank promises about ISIS. Bomb the hell out of ISIS. I'm would bomb the Out of them. Reporter: U.S. Forces are on the ground in the blast zone. They're gathering intelligence and assessing just how effective this weapon, the mother of all bombs, is.

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