Kyiv and the West accuse Russian forces of committing war crimes in occupied Ukrainian territory, which Moscow denies. Kherson, Zaporizhzhia, Luhansk and Donetsk are the four regions that Putin proclaimed annexed last September following what Ukraine said were sham referendums. Russian forces only partly control the four regions. HEAVY ARTILLERYFighting has raged in and around Bakhmut in Donetsk region for months, with Ukrainian forces holding out despite regular claims by Russia to have taken the city. "Any use of chemical, biological or nuclear weapons by Russia would be met with severe consequences," they said.

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