US President Barack Obama told German Chancellor Angela Merkel on Thursday that the United States and its allies should prepare new sanctions against Russia if it escalates the crisis over Ukraine.

US President Barack Obama told German Chancellor Angela Merkel on Thursday that the United States and its allies should prepare new sanctions against Russia if it escalates the crisis over Ukraine.

"The president underscored the need for the United States, European Union and other global partners to be prepared to meet further Russian escalation with additional sanctions," the White House said in a statement about the phone call.

"The leaders again called for Russia to move its troops back from the border region," it added.