Russia has fired cruise missiles from the Mediterranean Sea at Islamic State positions in Syria, the defence ministry said.
Two frigates and a submarine launched six cruise missiles at IS installations in Syria's Hama province, destroying command centres and ammunition depots, the ministry said in a statement.
It did not say when the missiles were launched.
Moscow has fired missiles from the Mediterranean at militants' positions in Syria before, including launches from a submarine and a frigate in May at targets in the area of the ancient city of Palmyra.
Russia is one of the strongest backers of Syrian president Bashar Assad's government and has been carrying out air strikes in the country since September 2015.
Separately, a senior Russian politician said Moscow is "nearly 100%" sure that the top IS leader was killed in a Russian air strike last month.
The defence ministry first made the claim last week, saying that Abu Bakr al-Baghdadi's death in the May 28 strike on the outskirts of the Syrian city of Raqqa was still "being verified through various channels".
Viktor Ozerov, head of the defence and security committee at the upper chamber of the Russian parliament, told the Interfax news agency that Russia's intelligence about al-Baghdadi's death is "nearly 100%" certain.
"Russia would not want to be on the list of the countries that have said before that he was killed and then al-Baghdadi would resurrect," Mr Ozerov added.
The whereabouts of the shadowy al-Baghdadi, with a 25 million dollar (£19.6 million) US bounty on his head, have not been known.
His last public appearance was almost three years ago in the Iraqi city of Mosul, at the 12th century al-Nuri mosque from where he declared a "caliphate" in the territory that IS had seized in Iraq and Syria in July 2014.
That mosque, along with its famous leaning minaret, was destroyed on Wednesday night, blown up by IS militants as their control of Mosul increasingly slips away.
The mosque would have been a symbolic prize for Iraqi forces and the US-led coalition in the fight for Iraq's second-largest city.