US President Barack Obama spoke with Russian President Vladimir Putin by telephone early Thursday, the White House said. According to a statement from the White House, the leaders discussed the situation in Ukraine and additional U.S. sanctions on Russian individuals and entities announced Wednesday. "President Obama emphasized that he remains committed to a diplomatic solution and that sanctions were not his preferred course of action," the White House said. "President Obama noted, however, that in the face of extensive evidence that Russia is significantly increasing the provision of heavy weapons to separatists in Ukraine and Russia's failure to take other steps set out by the United States and Europe to de-escalate the crisis, it was necessary to impose additional sanctions, consistent with the clear statements from the United States and our allies following the G-7 meeting in Brussels."