The United States said it could not confirm reports that Ukraine had disabled vehicles in a Russian convoy inside Ukraine and warned Moscow that any intervention into Ukraine without Kiev's permission was unacceptable.
"Even as we work to gather information, we reiterate our concern about repeated Russian and Russian-supported incursions into Ukraine," White House spokeswoman Caitlin Hayden said in a statement.
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Highs of 7 Celsius (45F).
The move, which had been expected, was made on the recommendation of FBI disciplinary officials.