US mega-strike in Afghanistan was 'very, very successful': Trump

President Donald Trump has said the United States military has been ‘successful’ lately because his administration has given them ‘total authorisation’, as he hailed the forces for dropping the largest non-nuclear bomb targeting an Islamic State complex in Afghanistan.

A GBU-43/B Massive Ordnance Air Blast Bomb (MOAB), nicknamed ‘Mother Of All Bombs’, was dropped on a tunnel complex of Islamic States-Khorasan, a regional affiliate of the terror group, in Achin district of Afghanistan’s Nanagarh province, close to the border with Pakistan.

Pentagon spokesman Adam Stump said yesterday that it was the first-ever combat use of the bomb. A MOAB is a 21,600-pound, GPS-guided munition that is America's most powerful non-nuclear bomb.

Trump said he authorised the use of the bomb in Afghanistan and called the mission ‘very, very successful’.

“It was really another successful job, we are very proud of our military. We are so proud of our military, it was another successful event," Trump told reporters at the White House.

"Everybody knows exactly what happened, what I do is I authorise our military. We have the greatest military in the world, they've done a job, as usual, so we have given them total authorisation and that's what they're doing, and frankly, that's why they've been so successful lately," he said.

"If you look at what's happened over the last eight weeks and you compare that to what's happened over the last eight years, you'll see there's a tremendous difference. So we have incredible leaders of the military and incredible military, and we are very proud of them, and this was another very, very successful mission," Trump said.

The US President, however, said he does not know if this would send a message to North Korea.

"I don't know if this sends a message. It doesn't make any difference if it does or not. North Korea is a problem. The problem will be taken care of. I will say this; I think China has really been working very hard," he said.

The bomb was dropped by an MC-130 aircraft, operated by the Air Force Special Operations Command.

At his daily news conference, White House Press Secretary Sean Spicer said the bomb was dropped at around 7 pm local time in Afghanistan on Thursday.

"The GBU-43 is a large, powerful and accurately delivered weapon. We targeted a system of tunnels and caves that ISIS fighters used to move around freely, making it easier for them to target US military advisers and Afghan forces in the area,” Spicer said.

“The United States takes the fight against ISIS very seriously and in order to defeat the group, we must deny them operational space, which we did. The US took all precautions necessary to prevent civilian casualties and collateral damage as a result of the operation,” he said.

The strike is part of the ongoing efforts to defeat ISIS-K in Afghanistan, the US Central Command said.

Nangarhar, which borders Pakistan, is a hotbed of IS militancy. According to the Department of Defence, there are about 600-800 ISIS-K fighters in the region where bomb was dropped.