"What I do is I authorize my military", Trump told reporters on Thursday in response to a question about the use of the bomb.
Nicknamed 'the mother of all bombs, ' the weapon was dropped from an MC-130 aircraft in the Achin district of Nangarhar, bordering Pakistan.
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.
"Using "mother of all bombs" in Afghanistan to kill 36 militants - at $450,000 each - will not change its reputation as a white elephant", a Guardian op-ed argued.
U.S. President Donald Trump April 13 called the bombing "another successful job". Footage put out by the Pentagon showed the bomb slamming into a mountainside overlooking a river valley, causing a giant blast that overwhelms the landscape then sends up a massive column of black smoke.
"This was the right weapon for the right target", Nicholson said. "The strike has destroyed an IS headquarters, three IS hideouts along with several bunkers and deep tunnels as well as huge amount of weapons and ammunition", the Afghanistan Defence Ministry statement said.
The strike was created to minimise the risk to Afghan and US forces conducting clearing operations in the area while maximising the destruction of IS fighters and facilities, said the US Forces-Afghanistan, which is part of NATO-led Resolute Support.
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The bomb, known officially as a GBU-43B, or massive ordnance air blast weapon, unleashes 11 tons of explosives.
A similar report on Friday had quoted the Afghan officials as saying that no civilian has been harmed in the bombing. "It was an earsplitting blast", said Shah Wali, 46, who lives in the village of Goor Gari, 15 kilometers (9 miles) from the border with Nangarhar.
But former President Hamid Karzai accused the United States of using Afghanistan as "a testing ground for new and unsafe weapons".
Isis has claimed that the so-called "mother of all bombs" dropped by USA forces on a mountain hideout in Afghanistan did not kill any militants.
US Forces-Afghanistan Commander General John Nicholson has said that Thurday night's strike in Achin district in Nangarhar was part of their campaign to destroy ISIS in Afghanistan in 2017. CNN said the MOAB bomb was selected because the area targeted was in an extremely remote portion of the country, meaning risk to civilians was minimal.
An Islamic State (IS) activist from Kerala is believed to have been killed along with 36 IS militants when the USA unleashed a massive GBU-43 bomb, also known as the "mother of all bombs", on the terror group's position in a cave network in eastern Afghanistan. But not all of the US' allies agreed with the use of the MOAB. "Assessment of the casualties to the ISIS-K is in process", the Afghan Presidential Palace said in a statement. The US has more than 8,000 US troops in Afghanistan, training local forces and conducting counter-terrorism operations.
While Islamic State's ranks in Afghanistan do include foreign fighters, Johnson said most of the extremist group's recruits are former Taliban members who joined for financial reasons.