Russian president Vladimir Putin said Russia had a "sufficient stockpile" of cluster bombs and reserved the right to use them if such munitions, the use of which he said he regarded as a crime, were deployed against Russian forces in Ukraine.
Ukraine said on Thursday it had received cluster bombs from the United States, its biggest military backer, which says the munitions are needed to compensate for shell shortages faced by Kyiv's forces at a time when they are mounting a counteroffensive.
Cluster munitions are banned in more than 100 countries because they typically release large numbers of smaller bomblets that can kill indiscriminately over a wide area. Some of them inevitably fail to explode and can pose a danger for decades, particularly to children.
Kyiv has said it will use cluster bombs to dislodge concentrations of enemy soldiers when trying to take back its own territory, but will not use them on Russian territory.
Putin told state TV Moscow would respond in kind if necessary.
"I want to note that in the Russian Federation there is a sufficient stockpile of different kinds of cluster bombs. We have not used them yet. But of course if they are used against us, we reserve the right to take reciprocal action."
Putin said he regarded the use of cluster bombs as a crime and that Russia had so far not needed to use them itself despite having suffered its own ammunition issues in the past.
Human Rights Watch says both Moscow and Kyiv have used cluster munitions. Russia, Ukraine and the US have not signed up to the Convention on Cluster Munitions, which bans the production, stockpiling, use and transfer of the weapons.
Putin also told state TV he saw nothing wrong in Russian specialists examining captured Western military equipment and missiles, such as the Storm Shadow missiles Britain supplied to Ukraine, in order to see if there was anything useful that could be used in Russia's own military hardware.
