Iran, Russia and China will hold joint naval exercises in the northern Indian Ocean "this autumn", Iranian semi-official Mehr news agency reported.
Mehr quoted Iranian Chief of Staff, Major General Mohammad Bagheri, as saying that other countries, including Oman and Pakistan, will join the drill, without giving further details.
The northern Indian Ocean extends to the Gulf and the Strait of Hormuz, and is a major waterway for oil exports to world markets.
Iranian state media reported that the three countries began joint exercises in December 2019, to deal with "unspecified threats in the region".
A Chinese military spokesman, at the time, described the exercises as "normal military communication".
The most recent round of these exercises took place in January.
The three countries have also expanded their diplomatic and economic relations, at a time when Iran is still under heavy US sanctions over its nuclear program, and Russia's invasion of Ukraine has cut off much of its trade with the West.
China believes the United States is applying double standards in dealing with the Iran nuclear deal.