Fresh analysis suggests ‘mother of all bombs’ caused far less damage than was originally reported – raising questions over why it was dropped in the first place

Questions for US military after doubt cast on efficiency of Afghan bombing

After dropping its largest conventional bomb ever used in combat in Afghanistan on 13 April, the US military said the massive ordnance air blast, or Moab, was a “very clear message to Isis” that they would be “annihilated”.

Defence secretary Jim Mattis said the bomb was “necessary to break Isis”. The Afghan government claimed the bomb killed 94 Isis militants, while harming no civilians.

But a new investigation by independent analysts casts doubt on the efficiency of the bomb, suggesting it inflicted far less damage than initially reported – and raising questions again over why the bomb was dropped.

Using satellite imagery, ground footage and 3D visualisation, Alcis, an institute for geographical analysis, surveyed the targeted area in Nangarhar province.

It found 38 buildings and 69 trees destroyed within a 150-metre radius, challenging statements from locals who told reporters the bomb had damaged houses up to two miles away.

The imagery also shows no 300-metre crater, as had been expected prior to the strike. Alcis believes damage done further away is a result of ground fighting.

Alcis was also sceptical of the Afghan government’s assessment that the bomb killed 94 Isis militants. “I’m staggered by that,” said Richard Brittan, the institute’s managing director. “I simply don’t understand where they can get that number from.”

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Government officials say they have pulled 94 Isis corpses out of the targeted tunnels.

Meanwhile, as the Guardian reported on a visit to Asadhkel village, 650 metres from the bomb site, other officials complained that the US military restricted or denied them access to the bomb site, where fighting continues.

The US has yet to put out a casualty estimate. The US military spokesman in Kabul, Capt William Salvin, would not comment on the Afghan numbers but said: “We have not been able to go in and do that assessment, and we’re probably not going to.”

He said it was “too dangerous” and that the military had “better things to do with our time”.

Alcis called the claim of no civilian casualties “anomalous”. The strike happened less than a month before harvest. Although many farmers had fled earlier fighting the valley, many would have returned to camp out near their crops, Brittan said.

“It’s the only place to be if you want to tend to those fields,” he said. “It is entirely possible that working-age male farmers could be counted as militants”.

Salvin said he was confident there had been no civilian casualties because the US had conducted persistent surveillance over the site for over a week before the strike.

“People are not shy about reporting civilian casualties in the country. And there have been no such reports,” he said.

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The analysis once again raises the question why the Moab was used. In Afghanistan, Isis constitutes a minor military threat compared to the Taliban. There has been speculation that the US wanted to send a signal to other powers in the region, but Salvin insisted the Moab was used for a “specific tactical purpose on the battlefield”.

Brittan, meanwhile, said that argument only made sense if the US wanted to deploy Moabs on hundreds of similar settlements in the targeted Mahmand valley, which would put years of development work at risk.

“If their approach is that they are going to level this valley with all its settlements, then Moabs galore,” he said. “But getting people back to making a living off the land is what you’ve got to focus on.”