US President Barack Obama has apologised to the president of aid agency Medecins San Frontieres (MSF) for a bombing that killed at least 22.
The US has said the bombing, which took place in the Afghan city of Kunduz, was a mistake and it was attempting to strike the Taliban.
MSF wants the bombing to be investigated as a war crime.
Mr Obama has also apologised to the president of Afghanistan.
"If it is necessary to hold individuals accountable, that will be done," said White House spokesman Josh Earnest.