A US attack on a hospital in Afghanistan which killed 42 people occurred because of human errors, process errors and equipment failures, a top general said.
General Joseph Votel said none of the crew knew they were striking a trauma centre, adding that " this was an extreme situation" complicated by combat fatigue among US special operations forces.
He headed US Special Operations Command at the time of the attack last autumn and took over US Central Command in March, which oversees military operations in Afghanistan.
Mr Votel said investigators concluded that certain personnel failed to comply with the rules of engagement and the law of armed conflict.
However, they also determined that these failures did not amount to a war crime, he said.
"The label 'war crimes' is typically reserved for intentional acts - intentional targeting (of) civilians or intentionally targeting protected objects or locations," Mr Votel said.
"Again, the investigation found that the incident resulted from a combination of unintentional human errors, process errors and equipment failures, and that none of the personnel knew they were striking a hospital."
He expressed "deepest condolences" to those injured and to the families of those killed.
No criminal charges have been levelled against US military personnel for mistakes that resulted in the attack on the civilian hospital in Kunduz, operated by the medical charity Doctors Without Borders, on October 3 2015.
The group called the attack a war crime and demanded an independent investigation.
Mr Votel said the trauma centre was on a US military no-strike list but that the gunship crew did not have access to the list because it launched its mission on short notice and as a result did not have the data loaded into its onboard systems.
He said the military has sought to avoid similar mistakes in the future by requiring that such data be pre-loaded into aircraft.
Central Command released a redacted version of the full investigation report on Friday, including details about what exactly led the AC-130 gunship to bomb the hospital and how those mistakes were made.
"The investigation determined that all members of both the ground force and the AC-130 air crew were unaware that the aircraft was firing on a medical facility throughout the engagement," Mr Votel said.
"The investigation ultimately concluded that this tragic incident was caused by a combination of human errors, compounded by process and equipment failures."
He said 16 military members, including officers as well as enlisted, have been disciplined.
He added that none of their names will be released to protect the privacy of the individuals and in some cases because they are still assigned to sensitive or overseas positions.
According to one senior US official, a two-star general was among about the 16 disciplined military personnel.
A number of those punished are US special operations forces. No one was sent to court-martial, officials said.
However, in many cases a non-judicial punishment, such as a letter of reprimand or suspension, can effectively end a military career.
The crew of the AC-130, which is armed with side-firing cannons and guns, had been dispatched to hit a Taliban command centre in a building 450 yards from the hospital, the US military said in November.
Hampered by problems with their targeting sensors, the crew relied on a physical description that led them to begin firing at the hospital even though they saw no hostile activity there.
Officials have said the attack was caused by human error, and that many chances to prevent the attack on the wrong target were missed.
A separate US report on the incident said the AC-130 aircraft fired 211 shells at the hospital compound over 29 minutes before commanders realised the mistake and ordered a halt.
Doctors Without Borders officials contacted coalition military personnel during the attack to say the hospital was "being 'bombed' from the air", and the word finally was relayed to the AC-130 crew, the report said.
The attack came as US military advisers were helping Afghan forces retake Kunduz, which had fallen to the Taliban on September 28.
It was the first major city to fall since the Taliban were expelled from Kabul in 2001.
Afghan officials claimed the hospital had been overrun by the Taliban, but no evidence of that has surfaced.
The hospital was destroyed and Doctors Without Borders ceased operations in Kunduz.
The head of an international humanitarian organisation whose hospital in northern Afghanistan was razed to the ground by a US airstrike earlier this month has claimed the attack was deliberate.