President Obama spoke by telephone with German Chancellor Angela Merkel to discuss the ongoing situation in Ukraine, White House spokesman Jay Carney told reporters.
Carney said the call, which happened while Obama was traveling on Air Force One from Austin, Texas, was "just to check in on the situation." He said more details would be provided later on Thursday.
Tensions remain high in eastern Ukraine after at least three died in a day of shooting during what was supposed to be an Easter truce.
In an exclusive interview with NBC News, the Ukrainian Prime Minister warns of the dangers of unchecked Russian expansion and aggression.
Russia, the US and the EU say that all sides have agreed to steps to "de-escalate" the crisis in Ukraine at talks in Geneva.