Kyiv’s biggest European allies lined up with President Volodymyr Zelenskiy to reject key elements of a US-Russian plan to end the war in Ukraine as Washington threatened to halt military support to force acceptance of the deal.

Ukrainian President Volodymyr Zelensky has warned that Kyiv risks losing US support over a White House plan on how to end the war with Russia.

The draft document states that any future “significant, deliberate, and sustained armed attack” by Russia on Ukraine “shall be regarded as an attack threatening the peace and security of the transatla...