Estimates of how many Russian troops are near Ukraine's border range from 40,000 to 88,000.
"It's well known and well acknowledged that you've seen a range of troops massing along that border under the guise of military exercises. But these are not what Russia would normally be doing. And, you know, it may simply be an effort to intimidate Ukraine or it may be that they've got additional plans," Obama said during an interview with CBS that aired Friday.
Russia, Obama stated, needs "to move back those troops and to begin negotiations directly with the Ukrainian government, as well as the international community."
On Thursday, the United Nations General Assembly overwhelmingly passed a resolution to reaffirm Ukraine's territorial integrity and declare Russia's annexation of Crimea invalid.
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