Russia's Defence Minister Sergei Shoigu made an unannounced visit to Iran to deliver a "special message" from President Vladimir Putin to President Hassan Rouhani. The ongoing Syrian conflict dominated the talks between the top authorities.

Shoigu landed in Tehran on 21 February and met his counterpart Hossein Dehghan separately. Only days ago the Iranian defence minister visited Russia, where the two countries agreed to step up their military cooperation.

On Shoigu's tour, the semi-official IRNA news agency said he outlined "the situation regarding stability in the region and the process of negotiations for a ceasefire in Syria". Shoigu also briefed the Iranian leader over the challenges in easing the crisis in Syria. Nevertheless, it was not elaborated what "special message" he was carrying from Putin.

Rouhani responded to the Russian authority by saying: "Resolving the crisis in Syria can only be achieved through political negotiations and respect for the rights of the Syrian people who must ultimately decide their country's future."

Russia recently approved the delivery of S-300 anti-aircraft missile batteries to Iran and Shoigu's trip is also thought to be intended at finalising some aspects of the agreement. In addition to that, Moscow is also mulling to sell several high-profile warplanes, tanks and missile systems to Tehran against the backdrop of the recent lifting of UN-imposed sanctions on Iran.

The two countries, both partners of Syrian President Bashar al-Assad, have shown greater interest in bolstering their military cooperation in the wake of the Syrian turmoil. Putin had recently said a closer cooperation between Moscow and Tehran would play a pivotal role in the regional security.