Russian Defense Minister Sergei Shoigu has arrived in Tehran, days after his Iranian counterpart visited Russia.
Iranian television reported that Shoigu met with President Hassan Rohani on February 21, and was due to also hold talks with Defense Minister Hossein Dehghan during his trip to discuss the "situation in the region."
The visit comes as U.S. Secretary of State John Kerry said a "provisional agreement" had been reached with Russia on terms of a cessation of hostilities in Syria.
Russia and Iran have both been strong backers of President Bashar al-Assad during the nearly five-year conflict.
Shoigu and Dehghan held talks in Moscow on February 16, during which the sides discussed the implementation of a January 2015 intergovernmental agreement on military cooperation, according to the Russian Defense Ministry.
Russia has a contract with Iran to deliver long-range S-300 air-defense missiles, and Tehran has said it plans to ink a deal with Moscow for the purchase of Su-30 fighter jets.