Washington, March 10 (RHC)-- The United States and France have warned of possible new measures against Russia if Moscow fails to 'defuse' the crisis in Ukraine. U.S. President Barack Obama discussed the escalating Ukraine crisis in a telephone call with French President Francois Hollande over the weekend.

The two leaders insisted on the "need for Russia to withdraw forces sent to Crimea since the end of February and to do everything to allow the deployment of international observers," the French presidency said in a statement.

"If there's a lack progress in this direction, new measures will be taken which would noticeably affect relations between the international community and Russia, which is in no one's interest."

Meanwhile, the White House said later in the day that Obama discussed the crisis in phone calls with British Prime Minister David Cameron and Italian leader Matteo Renzi.

Russia has already said it will not capitulate to the Western countries' language of threats and sanctions over Ukraine. Moscow has also warned Washington that any sanctions against Russia would backfire.

Washington has sent U.S. fighter jets to allied countries located near Ukraine, imposed visa restrictions on Russians, ordered sanctions on individuals it said were involved in the Russian military intervention in Ukraine, and condemned the proposed referendum in Crimea to break away from Ukraine and join Russia. And the Pentagon has suspended military ties with Russia, including joint maneuvers and port visits.