Practically all public visible encryption had to come from overseas during the crypto wars, because US crypto was not allowed to be exported. So everybody used european or australian crypto, and we still do. gpg, openssl, gnutls, truecrypt, ssleay, ...
GPG is an implementation of PGP (via the OpenPGP specification). PGP was developed in the US, and was, in many ways, the opening salvo of the "first crypto war".
[0] https://en.wikipedia.org/wiki/GNU_Privacy_Guard