On 8 December, a Ukrainian jet bound for Kiev crashed soon after taking off from Tehran. The majority of passengers were from Iran and Canada. Ukraine initially blamed engine failure, but later retracted the statement. President Zelensky warned against ‘speculation or unchecked theories regarding the catastrophe’ until official reports were ready. As a sign of the potential difficulties facing crash investigators, the head of Iran's civil aviation organisation was quoted as saying that the plane's black box would not be handed over either to Boeing or the Americans. An Iranian official blamed an engine fire, adding, ‘Had the accident happened due to a missile strike, the plane would have exploded in the air’.