Obama hopes that European nations will support the sanctions, and if Russia invades eastern Ukraine, it is likely that the Europeans will support tougher sanctions against Russia, experts said.

In an interview with CBS News last week, Obama said it was "absolutely clear" that Russia had violated Ukraine's sovereignty and territorial integrity by "annexing Crimea" last month and was continuing to do so by supporting "non-state militias" in eastern Ukraine.

Moscow, however, has rejected accusations that Russia was destabilizing Ukraine. In a telephone conversation with Obama on Monday, Russian President Vladimir Putin urged the United States to use its influence to prevent bloodshed in Ukraine.

Washington and Moscow began to butt heads after Russia deployed troops to Crimea a few weeks back, with the US blasting the move as contrary to international law and imposing sanctions, while Russia defended the move as an effort to protect ethnic Russians in the region.

David Clark, chairman of the Russia Foundation, told Xinhua that Russian policy makers see the United States as strong, but not as strong as it once was, adding that Washington is no longer focused on Europe as its main strategic priority following Obama's rebalance to Asia.

He added that Moscow is testing the United States and European responses to gauge their willingness to support Ukraine and challenge Russian behavior before deciding what to do next.

So far the Obama administration has ruled out military intervention in the Ukrainian crisis and repeatedly called for a diplomatic solution, as it faces hefty military budgetary cuts and war weary public after more than a decade of military involvement in Iraq and Afghanistan.