U.S. and European security agencies estimate Russia has deployed military and militia units totaling more than 30,000 people along its border with eastern Ukraine, according to U.S. and European sources familiar with the developments.
The current estimates represent what officials on both sides of the Atlantic describe as a continuing influx of Russian forces along the Ukraine frontier, the sources said.
Quoting two unnamed Obama administration officials, CNN has reported that, according to a U.S. assessment of the situation, the likelihood of a Russian incursion into eastern parts of Ukraine is now greater than it has been before.
The officials have been quoted as having seen several worrying signs in the past three to four days.
An incursion into eastern Ukraine, if deep enough, could enable Russia to establish a land connection to Crimea, which in a move widely condemned in the West it formally annexed last week. Currently, Russia has access to the Black Sea peninsula only by air and sea.
In coming hours, both houses of the U.S. Congress are expected to approve financial aid for Ukraine and sanctions against Russia for its annexation of Crimea.