As the U.S. and Europe consider financial sanctions to punish Russia for trampling on Ukraine's sovereignty, they are coming up against an uncomfortable reality: Those sanctions tend to cut both ways. But how deep do they cut?

Russia is far more financially intertwined with the West than it was back in the days of the Soviet Union. Russian entities, including individuals and companies, had assets of about $160 billion in foreign banks as of September 2013, according to data from 44 countries that report to the Bank for International Settlements:

Freezing those assets could focus the minds of powerful Russians on the consequences of President Vladimir Putin's actions. Unfortunately, the Russians could respond by reneging on their obligations to foreign banks -- a danger one Kremlin aide specifically noted earlier this week. Banks' exposure to Russia stood at $242 billion in September 2013, according to separate BIS data that include 24 reporting countries:

The result is that U.S. and European banks would be among the most affected by financial sanctions. Here's a breakdown of their exposure to Russia by country:

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