Ukrainian President Volodymyr Zelensky is facing an increasingly untenable situation: the leader of his country’s most-needed ally believes he’s responsible for continuing a war he didn’t start, doesn’t like the way his country is trying to defend itself, and has called for him to be replaced.

Zelensky’s relationship with President Donald Trump has been tumultuous for years, but several recent decisions by Trump, which come as Russia continues its attacks on Ukraine’s energy infrastructure, have demonstrated a fissure between them that could be unrecoverable.