How exposed is the US to European debt defaults?

The risk that the US government will default on some of its debt obligations lingered last week as the stand-off over the raising of the debt ceiling appeared to intensify. At the same time, it has become more likely that at some point the US might have to contend with a sovereign debt default by one or more euro-zone nations. We think the latter would have a meaningful impact on the US economy only if some of the larger euro-zone economies, such as Spain and Italy, were to default.