"I find the use of the largest non-nuclear bomb, the so called "mother of all bombs", on our soil reprehensible and counterproductive", Omar Zakhilwal, the Afghan envoy to Pakistan, said on Twitter.
Other analysts suggest that the MOAB device was employed on the IS hideout because that target was a ideal opportunity to demonstrate overwhelming US military might. We have the greatest military in the world and they have done a job as usual.
"This is a unique enemy position" in Nangarhar province, Williams said.
But the group has been steadily losing ground in the face of heavy pressure both from USA air strikes and a ground offensive led by Afghan forces.
Thomas Johnson, director of the Naval Postgraduate School's program for cultural and conflict studies, believes MOAB will not have a major impact on IS.
Public reaction to Thursday's strike has been mixed, with some residents near the blast praising Afghan and US troops for pushing back the Islamic State militants.
"The attack yesterday was more symbolic", Johnson added, "and actually had more domestic political implications [in the U.S.] than implications in Afghanistan".
"Many Taliban foot soldiers joined IS because it was offering $700 a month, which was a lot more money than the Taliban could offer", Johnson said. No one has any idea who might replace Mr Assad, or whether a weaker Assad regime means a stronger Isis - just as no one has any idea whether hitting Isis in Afghanistan strengthens the Taliban.
"I do not think that this massive bomb is going to change the dynamics at all", Goodfellow said. Goodfellow's CIP group is a nonprofit research and advocacy group based in Washington that tries to promote cooperation, transparency and accountability in global relations. "That's where we should be focusing our attention".
Achin is separated from Pakistan by a range of high mountains, one of the areas where Taliban and al Qaeda fighters fled when the United States first intervened in the country in late 2001. But the US military brought out the biggest conventional bomb in its arsenal for the first time to hit the Islamic State group, which has a far smaller, but growing presence in Afghanistan - an apparent reflection of President Donald Trump's vows for a more no-holds-barred campaign against the group. "We're talking today about the GBU-43, there's another one, the GBU-57, that's the Massive Ordnance Penetrator, and that will be very interesting to use practically because that one goes against deepened, protected targets - that's a bunker buster".
"This was the right weapon against the right target", Gen. John Nicholson, commander for United States forces in Afghanistan, told a press conference. "This is the right munition to reduce these obstacles and maintain the momentum of our offensive".
"We have incredible leaders in the military, we have an incredible military and we're very proud of them, and this was another very, very successful mission", Trump said Thursday.
Away from the area directly impacted by the blast, the reaction was more mixed. Another person was wounded when a second bomb exploded in Lashkar Gah, the capital of Helmand, he said. "There are no civilians here".
Russia's defense ministry said its development did not contradict any worldwide arms agreement, insisting it's not the start of a new arms race and that the FOAB would replace smaller nuclear bombs in its arsenal.