Washington's decision to supply Ukraine with cluster munitions is an "act of desperation" that will have no effect on Moscow's campaign in Ukraine, Russia's foreign ministry said on Saturday.
"It is an act of desperation and shows weakness against the backdrop of the failure of the much-touted Ukrainian counteroffensive," ministry spokeswoman Maria Zakharova said in a statement.
"The latest 'miracle weapon' which Washington and Kyiv are betting on, without thinking about the grave consequences, will have no effect on the special military operation," she said, using Russia's official term for its campaign in Ukraine.
Zakharova said the decision showed the "aggressive anti-Russian course taken by the US, which is aimed at prolonging the conflict in Ukraine as much as possible".
She also said Ukraine's promises to use the controversial ammunition responsibly "are not worth anything".
Russia itself uses cluster bombs in Ukraine but they are banned in many parts of the world.
Humanitarian groups have strongly condemned the US decision to supply cluster munitions, which can go undetonated and potentially endanger civilians for years to come.
US President Joe Biden admitted that supplying Ukraine with weapons capable of covering several football fields with hundreds of multiple small explosives was "a difficult decision".