ISIS-held areas around the ancient city of Palmyra have been targeted by Russian jets as part of Moscow's ongoing bombing in Syria.
It was the first time Russia confirmed a strike close the UNESCO world heritage site and is one of 237 targets the Russian air force have hit in 131 sorties over the last two days alone, according to a statement on Monday.
"Su-25 jets hit a fortified ISIS position in the Tadmur area of Homs province," said Moscow's defence ministry, using the Arabic name for Palmyra.
"As a result of a direct strike, a fortification, an underground bunker and anti-aircraft artillery were destroyed."
However Russian planes had also targeted Palmyra on Monday, said the head of the Britain-based Syrian Observatory for Human Rights.
An activist from Palmyra, Khaled al-Homsi, supported this assertion and said Russian strikes hit the citadel on the western edge of the UNESCO site.
"The extent of the damage could not be verified," he told AFP.
The latest raids follow diplomatic talks in Vienna on Friday, aiming to bring the 4 year conflict to an end.
For the first time the discussion involved other main parties involved in the crisis, including Russia and Iran who are both strong allies of President Bashar al-Assad.
Although the talks were largely non-conclusive, the participants agreed to ask the United Nations to broke a peace deal between the government's regime and the opposition with the aim to clear the way for a new constitution and democratic elections.
However the main opposition groups, who were not represented at the talks, insist that elections are just a foil by Russia and Iran and would only serve to uphold Assad's government.
Many western backed opposition groups have been the target of Russian bombing in Syria as the air force has targeted areas known not to be under ISIS occupation. Moscow has said it is helping troops loyal to Assad fight what it calls the "terrorists."
The US have formed a separate coalition from Russia to bomb ISIS in Syria.