An ongoing investigation has so far found that the munition did not go off target, but hit the school because old intelligence showed it was a military target, four sources said.
Witnesses and an Iranian education ministry official previously said the school was located in a compound that was a base for the Islamic Revolutionary Guard Corps about 15 years ago.
Two sources said the Defense Intelligence Agency was one of the agencies responsible for providing target information that may have led to the school strike, although other sources may have contributed to verifying the target, including intelligence from US allies.
A US official said Israel was involved in the process of selecting targets that led to the US strike on the school. The Defense Intelligence Agency gathered intelligence and found that the targets were valid at the time, the official said.
The US usually goes through a validation process involving multiple intelligence agencies before approving a strike. The US official said it was unclear where the breakdown occurred in the target selection process that could have triggered a US hit on the school.
NBC News reached out to the Israeli embassy in Washington, DC, which had no immediate comment.
President Donald Trump has previously denied that the US was behind the strike and suggested without evidence that Iran or “other countries” could be responsible.
“In my opinion, based on what I saw, Iran did it,” he told reporters aboard Air Force One on Sunday.
According to experts who reviewed footage obtained by NBC News and others, the missile fragments that Iranian state media said hit the school bore the markings of an American Tomahawk missile. The US is the only country currently involved in a conflict using Tomahawk missiles.
“Whatever the report shows, I’m willing to live with that report,” Trump said Monday when pressed on the strike.
A United Nations group of experts warned last week that “an attack on a school operating during class time raises the most serious concerns under international law,” adding that “deliberate attacks on educational buildings” would be considered a war crime.
