The Pentagon says the US air strike which hit a hospital run by Medecins sans Frontieres and killed 42 people was not a war crime.
General Joseph Votel said that the "tragic strike" was due to human and technical error and confirmed that disciplinary charges are being brought against US personnel.
US forces thought the hospital building had been seized by the Taliban however as the mistaken strike was "unintentional", no war crime had been committed.
"The investigation found that the incident resulted from a combination of human errors, process errors and equipment failures and that none of the personnel knew they were striking a hospital," he said.