US Secretary of State John Kerry has accused Russia of “deception” and “destabilisation” in Ukraine and hinted at imposing more sanctions.
Speaking at the State Department in Washington, Mr Kerry warned Moscow time was running out for it to change course.
“Russian President Vladimir Putin and Russia face a choice,” he said in unusually blunt language.
“If Russia chooses the path of de-escalation … all of us will welcome it. But if Russia does not, the world will make sure that the costs for Russia will only grow.”
Mr Kerry added this would be a “grave” and “expensive mistake”.
He also said the Kremlin has not honoured an agreement aimed at defusing the crisis, echoing earlier comments by President Barack Obama.
The Geneva accord between Russia, Ukraine, the US and EU compelled armed groups to put down their weapons and vacate official buildings.
The US says Moscow is stoking unrest and separatist sentiment in the east of Ukraine after its annexation of Crimea.
Russia accuses Washington of encouraging a pro-Western government to adopt anti-Russian policies… see more