Publishers face fines of up to half a million dollars and up to ten years in prison if they edit any works from Iran, Libya, Sudan and Cuba. They can publish them "as is", but it's forbidden to edit (for spelling, punctuation, grammar, etc.), illustrate or peer-review any works from embargoed nations.
Peer review is one of the fundamental processes in the advancement of scientific theories, and editing is a basic function of publishing, which directly affects the publishers' reputation (and therefore, their income). But here in "the land of the free", they can also be considered collaboration with the enemy, and therefore punishable by fines and imprisonment.