US law on re-exporting crypto software?

An article in the current issue of the German journal `Datenschutz und
Datensicherheit' claims that exporting crypto software from anywhere
outside the US to a third country violates US law if the software
contains (only marginal amounts of) US-developed code, such as a C
standard library, and that anyone distributing crypto software that
has been compiled with an American compiler had better not visit the
United States.  Is that true?