Russia, Iran, and China will hold joint naval war games on Dec. 27, Russia's TASS news agency cited a senior Iranian naval official as saying on Tuesday.
TASS did not report where the drills would be held.
The announcement came as Russian President Vladimir Putin on Tuesday criticised NATO's continued expansion, something he suggested was pointless given the absence of a threat from Moscow following the 1991 collapse of the Soviet Union.
Speaking at a meeting of Russian military leaders in the Russian Black Sea resort of Sochi, Putin said NATO expansion posed a threat to Russia, but said he hoped that a shared interest in common security would prevail.
Despite tensions, Putin said Russia remained ready to cooperate with the military alliance.
He was speaking as U.S. President Donald Trump lashed out at European allies before a NATO anniversary summit in London, singling out France's Emmanuel Macron for "very nasty" comments on the alliance and Germany for spending too little on defence.