Russia’s Defense Minister Sergey Shoigu arrived on Sunday in Tehran for a surprise visit, Iran’s state television reported.
Shoigu is expected to meet President Sheikh Hassan Rouhani and his counterpart Hussein Dehghan during his trip to discuss the “situation in the region”, it said.
The trip comes days after Dehghan visited Moscow on Tuesday, during which Shoigu said Russia and Iran were ready to step up their military cooperation.
Russia has authorized the delivery of S-300 anti-aircraft batteries to Iran.
According to Russian and Iranian media, Iran also wants to buy Sukhoi 30 fighter jets from Russia.