Obama says Russia must 'move back' troops

US President Barack Obama says Russia must "move back" its troops from the Ukraine border and start negotiating.

Obama told CBS News that Russian President Vladimir Putin's decision to assemble forces on the border may "simply be an effort to intimidate Ukraine, or it may be that they've got additional plans."

Although estimates of troop numbers vary vastly, Obama said that "to de-escalate the situation" Russia should "move back those troops and begin negotiations directly with the Ukrainian government as well as the international community."

He also said Putin had been "willing to show a deeply held grievance about what he considers to be the loss of the Soviet Union," and the Russian leader should not "revert back to the kinds of practices that, you know, were so prevalent during the Cold War".

"I think there's a strong sense of Russian nationalism and a sense that somehow the West has taken advantage of Russia in the past and that he wants to in some fashion, you know, reverse that or make up for that," Obama said, referring to Putin..

"What I have repeatedly said is that he may be entirely misreading the West. He's certainly misreading American foreign policy," the US leader told CBS.

"We have no interest in circling Russia and we have no interest in Ukraine beyond letting Ukrainian people make their own decisions about their own lives."