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.
He went on: "For a week, Russian bombs have fallen overhead. Despite the constant barrage of Russian fire, we stand firm and united in our resolve to defeat the invaders. We will fight to the last breath to protect our country.
"But make no mistake: Other autocrats are watching, taking lessons. They can create a coalition of bad will — just look at how once-peaceful Belarus is now serving as a staging ground for Russian troops."
Mr Yermak, a lawyer whose mother was Russian, has been friends with the Ukrainian president for more than a decade. The pair met while both worked in TV and film production.
"Listen to what Mr. Putin is saying,' he continued. "For years, the West listened to Mr. Putin but didn’t hear him; it is just now waking up to the existential challenge he poses to the world order.
"Ukraine has never underestimated his intentions — not since Russian aggression against our country began in earnest in 2014 — nor his willingness to achieve domination by any means necessary.
"That’s because we know this war is not just about Ukraine. The Kremlin wants to create a new Russian empire."
The lawyer begged Ukraine's Western allies to pay attention to the "existential challenge" Putin "poses to the world order".
"Again, make no mistake: Mr. Putin aims to advance this ideology by going for blood beyond Ukraine. He must be stopped," he insisted.
