Vice President Joe Biden vowed in a conversation with the Ukrainian president Wednesday to keep working with the United States' partners to "impose further costs" on Russia if it doesn't stop the flow of weapons to pro-Russian separatists across the border.
Biden emphasized that the U.S. and its allies had already asked Russia to curb the weapons traffic and use its influence on militant fighters in eastern Ukraine to end the violence. Russia has failed to comply with both requests.
"The vice president noted that the United States would work with our partners to impose further costs on Russia if it continued on its current course," the White House said in a statement about the conversation with President Petro Poroshenko.
The White House said the two leaders promised "to stay in touch" ahead of the European Union leaders' meeting on June 27.