The U.S. Federal Bureau of Investigation has launched an investigation into the killing of Shireen Abu Akleh, the veteran Al Jazeera reporter who was shot and killed in May during a firefight between Israeli troops and Palestinian terrorists, prompting outrage from Israel which has said it will not cooperate.

Defense Minister Benny Gantz called the American investigation “a grave mistake,” and noted that the IDF had already conducted an “independent and professional investigation, the details of which were presented to the Americans.”

“I made it clear to the American representatives that we stand behind the IDF soldiers, that we will not cooperate with any external investigation, and we will not allow interference in Israel’s internal affairs,” he added.

In May, 57 House Democrats called on the U.S. to launch a probe into the death of Abu Akleh, who also holds U.S. citizenship.

In September, the IDF released its findings, concluding that there was a “high probability,” but that it was not “unequivocal,” that Abu Akleh was “accidentally” killed by gunfire from Israeli troops during a firefight with Palestinian terrorists.

The investigation her death was hindered by the Palestinian Authority’s refusal to conduct a joint investigation with Israel as well as its months-long delay handing over the bullet for forensic examination. The PA eventually succumbed to pressure and agreed to hand over the bullet to a U.S. forensic team which concluded that it was too damaged to determine its origins.

The IDF report underlined the “wild and indiscriminate gunfire” and bombs that were thrown by members of the Islamic Jihad terror group.

The IDF said the investigation included extensive interviews with the soldiers on the ground as well as forensic and ballistic analyses. The probe also took into account information published by foreign media organizations, including video footage and audio files.

Soon after the release of the IDF’s report, the Biden administration called for Israel to change its rules of engagement, with State Department Deputy Spokesman Vedant Patel calling on Israel “review its policies and practices on rules of engagement to mitigate the risk of civilian harm, protect journalists and prevent similar tragedies in the future.” Prime Minister Yair Lapid lashed back that “no one would dictate” Israel’s open fire policy.

Abu Akleh, a longtime correspondent for Al Jazeera, was fatally shot in the West Bank city of Jenin, while covering IDF counter-terrorism operations that followed a deadly string of terror attacks in Israel which killed 19 Israelis. Eleven of the attacks against Israelis had been carried out by residents of Jenin.

“It is also important to emphasize and clarify that throughout the entire incident, IDF gunfire was fired with the intent of neutralizing the terrorists who shot at IDF soldiers,” the report said.

“An additional possibility is that Ms. Abu Akleh was hit by bullets fired by armed Palestinian gunmen toward the direction of the area in which she was present.”

State Department spokesman Ned Price said at the time that the U.S. “welcomed Israel’s review of this tragic incident.”

Key Democratic lawmakers, including Senators Chris Van Hollen (D-MC) and Patrick Leahy (D-VT), called for the U.S. Department of Justice to launch its own investigation. In addition, 13 “progressive” Democrats co-sponsored a bill calling for federal authorities to determine whether the 51-year-old journalist was killed with U.S weapons. Both Israeli and Palestinian Authority forces use such weapons.