US President Donald Trump on Thursday gave the order for the US military to drop a GBU-43 or Massive Ordnance Air Blast (MOAB) bomb on an IS cave complex in Nangarhar Province in Afghanistan, the first time such a bomb has been used in combat.

"The strike was designed to minimize the risk to Afghan and US Forces conducting clearing operations in the area while maximizing the destruction of ISIS-K fighters and facilities," the Pentagon said in a statement.

ISIS-K refers to ISIS-Khorasan, the terror group's affiliate in Afghanistan.