The United States military announced on Friday, March 13, that it has intensified its investigation into the devastating February 28 strike on an Iranian girls' school after media reports indicated that early findings suggest US forces were likely responsible. Iran reported that the attack on the Shajareh Tayyebeh School resulted in the deaths of 168 children. If confirmed that US forces caused the strike, it would be among the deadliest incidents involving civilian casualties during decades of US military operations in the Middle East. Reuters first revealed the initial results of the investigation on March 5.

Due to the seriousness of the issue, US Defence Secretary Pete Hegseth declined to discuss the preliminary findings. He stated that the government would not allow media coverage to influence or pressure officials into making conclusions about what occurred. Hegseth explained that a higher-level investigation will be conducted by a US general officer who is not part of US Central Command, the command responsible for operations involving Iran. Such an approach is typically used by the US military to maintain independence and objectivity in sensitive investigations.

He told reporters at the Pentagon that the command investigation would continue as long as needed to examine all circumstances surrounding the incident. Iran’s newly appointed supreme leader addressed the nation on Thursday and blamed foreign enemies for the school attack but did not directly accuse the United States. Three US officials told Reuters that the investigation referenced by Hegseth is an administrative inquiry known as a "15-6" investigation. This type of probe can lead to disciplinary measures if wrongdoing is confirmed and typically involves sworn testimony and interviews with those connected to the event. The officials spoke anonymously because they were discussing internal military procedures.

Admiral Brad Cooper, head of US Central Command, ordered the 15-6 investigation last week following the completion of the initial review. According to one official, an external officer was assigned to lead the investigation on Thursday. The decision to initiate a deeper investigation reflects the significant concern about the possibility that US forces may have been responsible for the tragedy and the need to fully understand how it happened.

Annie Shiel, the US advocacy director for the Center for Civilians in Conflict, said the investigation suggests there is recognition that an error may have occurred and that authorities want to determine the cause. It remains uncertain how US forces might have struck the school. Early findings indicate that outdated targeting information may have been used, possibly failing to distinguish between the school and a nearby Iranian military base in the southern town of Minab.

Video footage and other evidence suggest that a Tomahawk cruise missile may have hit the building. This highly advanced precision weapon is possessed by only a small number of countries, including the United States. The investigation is ongoing despite earlier remarks from President Donald Trump, who initially questioned whether the US could have been involved. His comments caused concern among some defence officials about whether he would accept responsibility if the US was found to be at fault.

At first, Trump suggested, without evidence, that Iran itself might have carried out the attack and even claimed that Tehran might possess Tomahawk missiles, which military experts say is highly unlikely. On Monday Trump publicly stated that he would accept the conclusions of the investigation, saying he was prepared to accept whatever the final report determined.

A second US official said Trump's comments indicated he may now be more willing to accept the initial findings. The official also noted that the public attention surrounding the investigation could make it politically difficult for Trump to reject the results once the probe is completed. The official added that the decision to launch a 15-6 investigation shows the administration considers the matter very serious, as the process will carefully examine what went wrong and how similar incidents can be prevented in the future.

A visual investigation conducted by Reuters and published Thursday revealed that the school had maintained an online presence for several years, including numerous photographs showing students and school activities. The Shajareh Tayyebeh School is one of 59 schools operated by the Persian Gulf Martyrs' Cultural Educational Institute, a network linked to Iran's Islamic Revolutionary Guard Corps, according to archived versions of the organization’s website. Images from the school's website show students gathered in the courtyard, which matches verified footage taken outside the building after the strike occurred. Satellite images from mid-2015 show that the building was separated by walls from the nearby military base and appears to have been functioning as a school since at least 2018, when murals first appeared on its outer walls.