An attempt to boost Afghanistan's cashmere industry by shipping goats from Italy to the war-torn state was among the "ill conceived" reconstruction projects launched by the US, which resulted in the loss of $800million (£563m).
The Task Force for Business and Stability Operations, a Pentagon agency, has been accused of wasting millions on development projects over a five-year period in Afghanistan.
Poor planning and waste tainted the scheme, with $6m being lost on the cashmere wool programme alone.
Oversight of the animals' transportation was so poor the small herd of rare blond Italian goats might have been eaten for all anyone knew, Special Inspector General for Afghan Reconstruction John Sopko said.
“We don’t know,” Sopko said. “This was so poorly managed.”
The Pentagon has disputed several of his findings.
Appearing before the US Senate on Wednesday, Sopko said he had "not been able to find credible evidence showing [the task force's] activities in Afghanistan produced the intended economic growth or stabilisation outcomes that justified its creation".
"On the contrary, [its] legacy in Afghanistan is marred by unfinished, poorly planned, and ill-conceived projects."
The task force was charged with boosting Afghanistan's economy, using about $800m in US taxpayer funds.
One of the senators on the committee lambasted the task force for spending $43m on a natural-gas filling station, calling the programme "dumb on its face", as the cost of converting cars to natural gas exceeds the average income of Afghans.
"This is a terrible waste of taxpayer money when we have so many other uses for it," she said, USA Today reports.
The task force has since been disbanded.