Ukraine President Volodymyr Zelensky's top aide has warned that Vladimir Putin would "go for blood beyond Ukraine'' if its allies don't do more to stop him.
"This war could be a prologue to a greater European or even global massacre," Andriy Yermak, the head of the Ukrainian presidential office, wrote in a New York Times guest essay penned from an underground bunker.
"Not since the end of World War II has Europe seen violence and naked territorial ambition at such a scale," he wrote.
