The President and Prime Minister Cameron of the United Kingdom spoke today regarding their deep concern about the situation in eastern Ukraine. The President commended the government of Ukraine's approach to today's discussions in Geneva, where it put forward constructive proposals to expand local governance and ensure the rights of all Ukrainians are protected. The leaders stressed that Russia needs to take immediate, concrete actions to de-escalate the situation in eastern Ukraine, including by using its influence over the irregular forces in eastern Ukraine to get them to lay down their arms and leave the buildings they have seized. As the President has said, we will look for the Russians to quickly follow through on their commitments in Geneva in this regard. The President and the Prime Minister agreed that the United States and Europe are prepared to take further measures to impose costs on Russia if this de-escalation does not occur in short order.
Barack Obama, Readout of the President's Call with Prime Minister Cameron of United Kingdom Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/305304