Russian and Chinese naval ships have conducted a second joint patrol in the Pacific Ocean as Iran joined a security group led by Beijing and Moscow.
Iran signed the "memorandum of commitment" to become a permanent member of the Shanghai Co-operation Organization (SCO), according to Iran's foreign minister.
Hossein Amir Hossein Amir-Abdollahian said the agreement sees Iran enter "a new stage of various economic, commercial, transit, energy".
Watch: Russia and China take part in joint live-firing exercise.
It comes as China and Russia conducted naval exercises between the two countries, with Russian state media releasing footage of the drills.
Russia's ministry of defence said the naval exercises are made up of "joint tactical maneuvering and organization of communications".
They also said the exercises would see the respective navies conducting "practical artillery firing, and provide deck helicopter flights".
It comes after Russia launched a week of war games, involving forces from China and other nations, earlier this month.