Russia has expressed concern over a US official's suggestion that the US should provide arms to Ukrainian forces combating pro-Russian separatists in eastern Ukraine.
According to The Guardian, Russian foreign ministry spokesman Alexander Lukashevich said in Moscow that the US official's sent a "very serious signal".
The statement came just hours before US vice-president Joe Biden's scheduled visit to Kiev on Thursday.
Lukashevich warned against "a major change in policy of the US administration in regard to the conflict" in Ukraine, the report said.
Lukashevich said that the move would be a direct violation of the agreements reached.
US State Department spokesman Jeffrey Rathke said the United States was still assessing better ways to support Ukraine, adding that nothing was "off the table".
