In the face of mounting evidence, Iran has acknowledged that it shot down the Ukrainian jetliner by accident, killing all 176 people aboard. The admission by Iran’s Revolutionary Guard undermines the credibility of information provided by senior officials, who for three days had adamantly dismissed allegations of a missile strike as Western propaganda. The acknowledgment could anger the Iranian public. Iran had promised harsh revenge after a U.S. airstrike killed an Iranian general in Iraq. But instead of killing American soldiers, its forces downed a civilian plane in which most passengers were Iranian.