U.S. State Department warns Americans against non-essential travel to Ukraine . ` ` There will be costs for any military intervention in Ukraine , '' President Barack Obama says . The United States has warned that a Russian invasion of eastern Ukraine could lead to the deaths and destruction of thousands of civilians. Ukraine accused Russian Black Sea forces of trying to seize two airports in Crimea but said Ukrainian security forces prevented them from taking control . Russian President Vladimir Putin to EU leaders : Ukraine must avoid an escalation of violence .
U.S. State Department warns Americans against non-essential travel to Ukraine . ` ` There will be costs for any military intervention in Ukraine , '' President Barack Obama says . The United States has warned that a Russian invasion of eastern Ukraine could lead to the deaths and destruction of thousands of civilians. Russian President Vladimir Putin to EU leaders : Ukraine must avoid an escalation of violence .