It's been a while since I read up on this, but I believe that under the Berne Convention, foreign copyrights of signatories are entitled to the same protections

It's been a while since I read up on this, but I believe that under the Berne Convention, foreign copyrights of signatories are entitled to the same protections that each signatory provides to domestic copyrights. In that case, the applicability depends on whether the recipient, not the copyright owner, is subject to US jurisdiction.