U.S.-supplied cluster munitions are in Ukrainian hands and being deployed in the field as part of Kyiv's battle against Russia, White House national security spokesman John Kirby said on Thursday.
"We have gotten some initial feedback from the Ukrainians, and they're using them quite effectively," Kirby said at a news briefing.
Kirby said the cluster munitions are having an impact on Russian defensive formations and maneuvering.
Ukraine has pledged to use the cluster bombs only to dislodge concentrations of Russian enemy soldiers.
Cluster munitions, which are banned in more than 100 countries, typically release large numbers of smaller bomblets that can kill indiscriminately over a wide area. Those that fail to explode pose a danger for decades.
Each side has accused the other of using cluster bombs in the conflict launched by Russia's invasion in February 2022.
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