Iran said it’s arrested a number of people linked to the Jan. 8 downing of a Ukrainian passenger jet, and the country’s president called on the judiciary to form a special court and fully investigate the disaster.

Hassan Rouhani said Tuesday that while U.S. policies toward the Islamic Republic were the root cause of the mistake, that didn’t excuse Iranian officials from confronting their own responsibility in the disaster. All 176 people on board were killed when Iranian defense units fired at the plane, bringing it down shortly after take-off from Tehran.

“I promise that the government, with all its ability and using everything at its disposal, will investigate this matter,” Rouhani told officials in remarks broadcast live on state TV. “This is not an ordinary case. The entire world will be watching.”

Iran is under intense international pressure to provide full accountability over the circumstances that caused the crash of the Ukrainian International Airlines plane. The country’s Islamic Revolutionary Guards Corps, which led a strike on U.S. bases in Iraq hours earlier, said it had mistaken the aircraft for a cruise missile.

Iranian officials at first fiercely denied that Iran was to blame, provoking outrage and protests in Iran once they accepted culpability. Security forces clashed with thousands of protesters over the weekend and unverified video footage has shown them using tear gas and live-round ammunition to disperse and intimidate crowds in Tehran, who were chanting against the country’s leadership and the IRGC.

Those arrested will continue to be questioned, a spokesman for Iran’s judiciary, Gholam-Hossein Esmaili, told reporters, according to the semi-official Mehr news agency. Esmaili, who did not specify how many people had been detained, added that Iranian and Ukrainian investigators had traveled to France with the flight’s black box and their work should provide more clarity on the tragedy.