The blast zone could stretch up to 300m – military experts say (stock image)
The target was an ISIS tunnel in Afghanistan, reports claim.
The use of the bomb, now confirmed in the US, is the first time EVER.
Military sources say the weapon is named "the father of all bombs".
The blast radius is believed to be over 300 meters.
The Pentagon has confirmed the blast happened in Afghanistan's Nangarhar – and the giant weaponry was used.
The bomb, known as the GBU-43B, is a 21,000 lb giant.
ISIS jihadis are believed to have been taken out.