Russia’s Vladimir Putin has telephoned President Barack Obama to discuss the US proposal for a diplomatic solution to the crisis in Ukraine.
Mr Obama suggested that Russia put a concrete response in writing, the White House said in a statement.
According to the Kremlin, Mr Putin suggested examining how the situation could be stabilised.
Russia’s annexation of Crimea from Ukraine has sparked international condemnation.
In the hour-long phone call, the US president urged Mr Putin to avoid the build-up of forces on the Russian border with Ukraine.
“President Obama underscored to President Putin that the United States continues to support a diplomatic path… with the aim of de-escalation of the crisis,” the White House said in a statement.
“President Obama made clear that this remains possible only if Russia pulls back its troops and does not take any steps to further violate Ukraine’s territorial integrity and sovereignty.” BBC