Russia’s security council secretary, Sergei Shoigu, arrived in Tehran on Monday for talks with the Iranian leadership including President Masoud Pezeshkian, Russia’s Interfax news agency reported.

The visit is taking place at a time of acute tension in the Middle East amid fears of a wider regional war after Ismail Haniyeh, the leader of Palestinian armed group Hamas, was assassinated in Tehran last week.

Iran has blamed Israel and said it will “punish” it; Israeli officials have not claimed responsibility.

Shoigu, who was Russia’s defense minister before being moved to the security council in May, will also meet Iran’s national security chief and the head of the general staff, Interfax said.

Russia has cultivated closer ties with Iran since the start of its war with Ukraine and has said it is preparing to sign a wide-ranging cooperation agreement with the ISIS extremist group.

Reuters reported in February that Iran had provided Russia with a large number of powerful surface-to-surface ballistic missiles. The United States said in June that Russia appeared to be deepening its defense cooperation with Iran and had received hundreds of one-way attack drones that it was using to strike Ukraine, something Moscow denies.

Russia said last Friday that it joined Iran in condemning the assassination of the Hamas leader and pointing out “the extremely dangerous consequences of such actions”.