The GBU-43/B, also known as the Massive Ordnance Air Blast, is launched successfully from a MC-130E Combat Talon I aircraft during a test at Eglain Air Force Base, Florida, U.S., November 21, 2003 in this handout photo provided April 13, 2017.
KABUL - As many as 36 suspected Islamic State militants were killed in Afghanistan when the United States dropped "the mother of all bombs," one of the largest non-nuclear devices ever unleashed in combat, the Afghan defence ministry said on Friday.
Thursday's strike came as US President Donald Trump dispatches his first high-level delegation to Kabul, amid uncertainty about his plans for the nearly 9,000 American troops stationed in Afghanistan.
The deaths have not been independently verified, but ministry spokesman Dawlat Waziri said no civilians were harmed in the massive blast that targeted a network of caves and tunnels.
"No civilian has been hurt and only the base, which Daesh used to launch attacks in other parts of the province, was destroyed," Waziri said in a statement.
He was using an Arabic term that refers to Islamic State, which has established a small stronghold in eastern Afghanistan and launched deadly attacks on the capital, Kabul.
The 21,600-pound (9,797-kg) GBU-43 bomb, was dropped from an MC-130 aircraft in the Achin district of the eastern province of Nangarhar bordering Pakistan, Pentagon spokesman Adam Stump said on Thursday.
PICTURED: The GBU-43/B, also known as the Massive Ordnance Air Blast, detonates during a test at Elgin Air Force Base, Florida, US, November 21, 2003 in this handout photo provided April 13, 2017. CREDIT: REUTERS/U.S. Air Force photo/Handout
The device, also known as the "mother of all bombs," is a GPS-guided munition that had never before been used in combat since its first test in 2003, when it produced a mushroom cloud visible from 20 miles (32 km) away.
The bomb's destructive power, equivalent to 11 tonnes of TNT, pales in comparison with the relatively small atomic bombs dropped on Japan at the end of World War Two, which had blasts equivalent to between 15,000 and 20,000 tonnes of TNT.
At a village about 3 miles (5 km) from the remote, mountainous area where the bomb was dropped, witnesses said the ground shook, but homes and shops appeared unaffected.
"Last night's bomb was really huge, when it dropped, everywhere, it was shaking," said a resident, Palstar Khan, adding that he believed no civilians were in the area hit.
Other residents said they saw militants climbing up and down the mountain every day, making occasional visits to the village.
"They were Arabs, Pakistanis, Chinese and local insurgents coming to buy from shops in the bazaar," said resident Raz Mohammad.
On Friday, the village was swarming with Afghan and international troops, as helicopters and other aircraft flew overhead.
The strike was part of a joint operation by Afghan and international troops, Afghan President Ashraf Ghani's office said in a statement.
"Afghan and foreign troops closely coordinated this operation and were extra cautious to avoid any civilian casualties," it said.
Former Afghan president Hamid Karzai condemned the use of the weapon on Afghan soil.
"This is not the war on terror, but the inhuman and most brutal misuse of our country as testing ground for new and dangerous weapons," he said on social media network Twitter.
The Taliban condemned the use of the bomb, saying in a statement, "Using this massive bomb cannot be justified and will leave a material and psychological impact on our people."
American officials said the bomb had been positioned for possible use in Afghanistan for "some time" since the administration of former president Barack Obama.
The United States has steadily intensified its air campaign against Islamic State and Taliban militants in Afghanistan, with the Air Force deploying nearly 500 weapons in the first three months of 2017, up from 300 in the corresponding 2016 period.
Thursday's strike was not the first time Islamic State fighters have been targeted by heavy American bombardment in Nangarhar, where a US special forces soldier was killed battling militants a week ago.
Last year massive B-52 bombers operating out of Qatar flew at least two missions in Afghanistan for the first time since 2006.
Such aircraft can carry as much as 70,000 pounds (32,000 kg)of bombs, missiles, or other weapons on each mission.
In March, US forces conducted 79 "counterterror strikes" against Islamic State targets in Nangarhar, killing as many as 200 militants, according to the US military command in Kabul.
American military officials estimate there are around 600 to 800 Islamic State fighters in Afghanistan, mostly in Nangarhar, but also in the neighbouring province of Kunar.
The United Nations has raised concerns that the American air campaign is swelling civilian casualties in Afghanistan.
Last year air strikes by the military coalition caused at least 127 civilian deaths and 108 injuries, up from 103 deaths and 67 injuries in 2015, the U.N. says.