Russian Defence Minister Sergei Shoigu said on Tuesday that Moscow would be forced to use "similar" weapons if the United States supplied cluster bombs to Ukraine, Russian news agencies reported.
The U.S. announced last week it would supply Ukraine with cluster munitions - explosive weapons that typically release large numbers of smaller bomblets over a wide area. They are banned by over 100 countries, including Britain and Japan.
Shoigu was quoted as saying that Russia was in possession of cluster munitions but had so far refrained from using them in its military campaign.
However the U.S. has previously accused Russia of using cluster munitions in Ukraine and said they have had a failure rate of up to 40%, leaving the ground littered with unexploded bomblets. Washington says the cluster munitions it is sending to Ukraine have a failure rate of less than 2.35%.
"In the event that the United States supplies cluster munitions to Ukraine, the Russian armed forces will be forced to use similar weapons against the armed forces of Ukraine as a response," Shoigu said on Tuesday.
"It should be noted that Russia has cluster munitions in service... for all occasions... They are much more effective than American ones...," he said.
Shoigu added that the Russian army was taking measures to protect its troops from such weapons.
Human Rights Watch says both Moscow and Kyiv have used cluster munitions during the nearly 17-month conflict in Ukraine, which Russia calls a "special military operation".
The U.S. Russia and Ukraine have not signed up to the Convention on Cluster Munitions.
U.S. officials say they granted Kyiv's request for cluster bombs after it became apparent that Ukraine - now waging a counteroffensive against Russia - was running out of regular artillery ammunition and production would not meet its needs.
Close U.S. allies including Britain, Canada and Germany have expressed their opposition to the use of cluster munitions.
In other comments, Shoigu said Russia was "significantly reducing" the potential of Ukraine's counteroffensive and that Russian forces had gained ground during their own counterattack in the direction of Lyman in Ukraine's eastern Donetsk region.
Reuters could not independently verify battlefield claims.
