Russia's acting Foreign Minister Sergei Lavrov urged Iran and United States to wind down tensions after Iranian forces accidentally downed a Ukrainian passenger jet. He said the tragedy was a serious red flag and a signal that everyone should start working on de-escalation. He criticised Washington for killing Major General Qasem Soleimani of Iran's Revolutionary Guards.<br />''          <br />'' Meanwhile, Iran's Supreme Leader Ayatollah Ali Khamenei has defended the country's armed forces after it admitted shooting down the plane by mistake. He described the crash as a bitter tragedy and claimed that Iran's enemies used the crash and the military's admission to weaken the Revolutionary Guard.<br />'' <br />'' On the other hand, Ukrainian Foreign Minister Vadym Prystaiko said that Ukraine wants Iran to issue a formal document admitting its guilt.<br />'' <br />'' The Ukraine International Airlines Boeing was travelling to Kyiv from Tehran on 8 January and crashed shortly after take-off. All 176 passengers on board were killed.<br />''  <br />