Iranian Major General Qassem Soleimani has flown to Moscow for talks with Russia's military and political leadership, three sources with knowledge of his trip said on Friday.
"General Soleimani traveled to Moscow last night to discuss issues including the delivery of S-300s and further military cooperation," one senior Iranian security official told Reuters, referring to an air defense system Russia is supplying Iran.
One Moscow-based Western diplomat said he understood Soleimani would meet Russian President Vladimir Putin and Defence Minister Sergei Shoigu. A Kremlin spokesman said a meeting with Soleimani was not on Putin's schedule.
Soleimani, the commander of foreign operations for Iran's elite Revolutionary Guards, flew to Moscow in July last year to help Russia plans its military intervention in Syria and forge an Iranian-Russian alliance to support Syria's President Bashar al-Assad.
He has been subject to an international travel ban and asset freeze by the UN Security Council since 2007. Washington designated the Quds Force, the unit of the Revolutionary Guards which Soleimani leads, as a supporter of terrorism that same year.
UN member states such as Russia are required to deny entry to blacklisted individuals and senior US officials expressed serious concern last year when it was first reported that Soleimani had visited Moscow.