A senior Obama administration official warned Russian leaders Sunday not to send armed forces into Ukraine to restore what they see as a compliant government, urging them to reject a Cold War view of the tumult in Ukraine as a struggle between East and West.

“That would be a grave mistake,” President Barack Obama’s National Security Adviser, Susan Rice, said on NBC’s “Meet the Press.” “It’s not in the interests of the Ukraine or of Russia or of Europe or of the United States to see the country split. It’s in nobody’s interest to see violence return and the situation escalate.”

Ms. Rice’s remarks came after bloody street protests in Ukraine culminated this weekend in pro-Russian President Viktor Yanukovych’s decision to leave the capital of Kiev.

Ms. Rice said that Mr. Yanukovych’s whereabouts are “not known at the present.” She made clear that the Obama administration isn’t mourning his departure from the scene, saying he had lost “enormous legitimacy … by turning on his people, by using violence in the streets against peaceful protesters and by flouting the will of the Ukrainian people.”