"A sad day. Preliminary conclusions of internal investigation by Armed Forces: Human error at time of crisis caused by US adventurism led to disaster. Our profound regrets, apologies and condolences to our people, to the families of all victims, and to other affected nations," Zarif  said in a twitter message today. 

The downing of Ukraine International Airlines flight PS752 with the loss of 176 lives came just hours after Iran carried out missile strikes on two airbases housing US forces in Iraq in retaliation to the US killing of its top military General Qassem Soleimani.