Only a select number of EU institutions offer internships to non-European students. You can find a list of the ones that will accept American students here
By the way, that page is where CES lists all of the external opportunities that we hear about: scholarships, fellowships, internships, travel funding, etc. Check it out sometime.
CES Staff can also help you think about internships and put you in contact with an alumni.
If you are thinking about pursuing an internship abroad, consider applying for Carolina Global Initiative Award!