The White House is talking tough, "The more they escalate, the longer this goes, the great this cost will be," said Senior White House Advisor Dan Pfeiffer
But the people of Crimea have spoken - 96% want to break away from Ukraine and join Russia.
The next step - Russia's parliament will likely vote to annex Crimea.
Today, the European Union is expected to reluctantly join the U.S. announcing travel bans and freezing assets against those pushing for a takeover. "That could be disastrous and our citizens at the end of the day would not blame the Russians, but us," said Hannes Swoboda, European Parliament.
"The sanctions need to be enforced, along with our European allies, because that will have the biggest bite," said Senator Robert Menendez, (D) New Jersey.
"All you can do is increase the cost significantly and hope that they don't move further into the Ukraine," said Senator Jeff Flake, (R) Arizona.
"Get some military assistance to Ukrainians, at least so they can defend themselves." Senator John McCain, (R) Arizona.
Despite the economic risk, some here fear President Putin has the upper hand. "He's ahead as he would walk into any negotiation with Kiev and we're playing catch-up," said Rep. Mike Rogers, (R) Michigan.
President Obama called Putin again Sunday. Both say they want a diplomatic solution.
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