As the United States moves closer to imposing economic sanctions against Russia, it's worth looking at just how weak a threat it is if Eurozone nations do not impose sanctions as well. The United States and Russia aren't big trade partners—last year total trade between the two of them totaled less than $40 billion. The E.U., on the other hand, is Russia's largest trading partner.
Here are Russia's exports from 1995 to 2011 from the Observatory of Economic Complexity:
And here are their imports during that timeframe as well:
The little blue areas in each graph is the United States. The purple is Europe. Without the E.U.'s cooperation in implementing sanctions, American sanctions won't hurt Russia very much. Of course, because the the E.U. economy is so interconnected with Russia's, it means any economic sanctions will also hurt the E.U. That's the reason that countries like Germany and the Nertherlands are withholding support for sanctions and instead pushing for a diplomatic solution. That may make sense for those countries, but it makes the U.S. threat of sanctions very weak.