On a day of fast-moving developments in Ukraine
U.S. President Barack Obama has urged his Russian counterpart Vladimir Putin to seek a diplomatic situation to the crisis.
The White House says that, during the hour-long phone call Thursday, Obama urged Putin to hold direct talks with the new government in Ukraine.
He also explained that Russia's violation of Ukraine's territorial integrity prompted the U.S. to take a number of punitive steps in response.
The phone call came a matter of hours after the pro-Moscow parliament in Crimea voted in favor of becoming part of Russia and proposes a referendum to rubber-stamp that move in just nine days' time.
Ukraine has called the decision "illegitimate."
Meanwhile, the European Union says it will consider sanctions on Russia if it doesn't de-escalate the situation quickly.