"Rather than wait for a Russian invasion of eastern Ukraine to implement additional sanctions, which seems to be U.S. policy at the moment, we must take action now that will prevent this worst-case scenario before it becomes a reality," Corker wrote.
Privately, some of Obama's advisers are also pushing for more robust penalties now to serve as a deterrent against a full-on Russian military incursion. But questions remain about Europe's commitment to take the kind of coordinated action that would stand the best chance of changing Putin's calculus.
Europe has a far deeper economic relationship with Russia than the U.S., meaning its sanctions would hurt Moscow more. But leaders on the still economically shaky continent fear that the impact of those sanctions could boomerang and hurt their own countries just as much.
European foreign ministers met Monday to debate whether additional sanctions should be enacted on Russia. A high-ranking European Union official said they did decide to sanction more Russians with asset freezes and visa bans, but they appeared to stop well short of targeting Russia's broader economy.
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