US drops biggest bomb on IS, as Trump denies it sends message to Syria

The US on Thursday dropped it largest non-nuclear bomb to kill dozens of Islamic State militants in Afghanistan, as Donald Trump said he cared little if it "sent a message" during ongoing tensions with Syria, Russia and beyond.

The GBU-43B Massive Ordnance Air Blast bomb - dubbed the "Mother Of All Bombs" - hit IS positions in Achin district in eastern Nangarhar province.

The $16m bomb killed 36 IS militants, collapsed tunnels and sent shockwaves a mile from the blast site. Afghan officials said no civilians were killed.

But it also came only a week after the US president ordered missile strikes against the Russian-backed president of Syria, Bashar al-Assad, in retaliation for a suspected chemical attack, and as China warned of the potential for conflict amid rising tensions over North Korea. 

Trump called the mission "very, very successful" in defeating IS in Afghanistan, but dismissed suggestions the attack carried any other meaning.

"I don’t know if this sends a message; it doesn’t make any difference if it does or does not," Trump said on Thursday. "This was another very, very successful mission."

However former CIA analyst Jack Rice told RT, the Russian state-funded broadcaster, that the attack in Afghanistan was a indeed meant to be felt in other areas of the globe.

"It's dramatic. It's massive. The idea that you are going to have one single bomb hit that is that large is catastrophic in its impact. And I think it was part of that purpose. It was about showing force and certainly the US air force did that.

"But this is never about just one theatre of operation, everything is connected. They know that the Syrians are watching. Yes, they know that the Russians are watching. This is an issue they are doing for effect, and I don't think that could be discounted.

The huge bomb, delivered via an MC-130 transport plane, has a blast yield equivalent to 11 tonnes of TNT, and the weapon was originally designed as much to intimidate foes as to clear broad areas.

"The explosion was the biggest I have ever seen," Achin governor Esmail Shinwari told AFP, adding the bomb landed in the Momand Dara area of the district.

An Afghan militant source told AFP from an undisclosed location that locals had described the ground shaking "like an earthquake", with people being knocked unconscious by the blast.