Canada, Sweden, Ukraine and Britain on Monday filed a complaint with the United Nations civil aviation agency against Iran over a 2020 plane crash that killed 176 people. In a joint statement, the four countries — which all had citizens aboard the flight — accused Tehran of “using weapons against a civil aircraft in flight in breach of its international legal obligations.” Four years to the day after the tragedy, the countries have opened “dispute settlement proceedings” with the UN’s International Civil Aviation Organization (ICAO) in Montreal. Canadian Prime Minister Justin Trudeau said the filing was “an important step in our commitment to ensuring that the families of the victims impacted by this tragedy get the justice they deserve.” The ICAO did not immediately respond to requests for comment Monday afternoon. All 176 people aboard the Ukraine International Airlines flight — mostly Canadians and Iranians — were killed when the Boeing 737-800 was downed shortly after takeoff from Tehran on January 8, 2020. Three days later, Iran admitted that its military had targeted the Kyiv-bound plane with two surface-to-air missiles by mistake. The Iranian Civil Aviation Organization has pointed in a report to the “alertness” of its troops on the ground, who shot the missiles amid heightened tensions between Iran and the United States at the time. “For four years now, Iran has refused to take full legal responsibility for the downing of Flight PS752 despite our numerous attempts to engage in negotiations on this matter,” Canada, Sweden, Ukraine and Britain said in the statement. In July, the multi-nation group appealed their case to the International Court of Justice, seeking reparations from Iran for the victims’ families.