WASHINGTON (Reuters) - The White House warned Russia on Friday that Moscow would face tougher sanctions if it failed to abide by a new international deal on Ukraine or moved to send Russian forces into the eastern part of the country.
"Those costs and sanctions could include targeting very significant sectors of the Russian economy," Susan Rice, President Barack Obama's national security adviser, told reporters.
She said Washington would be watching very closely "in coming days" to see whether Russia met its obligations to use its influence to get pro-Russian separatists in eastern Ukraine to disarm and abandon public buildings they had seized.
Separatists said on Friday they were not bound by the agreement brokered by the United States, Russia, Ukraine and the European Union in Geneva on Thursday.
Rice appeared to put the onus on Moscow, which has annexed Ukraine's Crimea peninsula, to make sure pro-Russian forces comply.
"We believe that Russia has considerable influence over the actions of those who have been engaged in destabilizing activities in eastern Ukraine," she said.
"If we don't see action commensurate with the commitments that Russia has made yesterday in Geneva, which we all welcome, then obviously we've been very clear that we and our European partners remain ready to impose additional costs on Russia," she said.
Moscow has massed tens of thousands of troops on its border with Ukraine. Rice said new sanctions could be triggered in the event of a dramatic escalation of the crisis, including "the potential for Russia to move its own forces on the border inside of Ukraine."
The Geneva agreement requires all illegal armed groups to disarm and end occupations of public buildings, streets and squares.
But with the separatists staying put in the east and Ukrainian nationalist protesters showing no sign of leaving their - unarmed - camps in the capital's Maidan Square, it was not clear that either side would be willing to move first.
(Reporting by Matt Spetalnick and Jeff Mason; Editing by Andrea Ricci)