Proliferation of nuclear weapons to terrorist organisations is far more dangerous than proliferation of nuclear weapons to states, even states like North Korea.
Of course the EU and member states must work to ensure that people moving from one country to another understand their obligations and their rights in areas like health, road safety and further education.
The E.U. has moved to combat global terrorism by instituting common European arrest and evidence warrants and creating a joint situation center to pool and analyze intelligence.
Indeed, American companies make three times as much profits from their investment in one E.U. country, Ireland, than they do from all their investments in China.
The E.U. is more than just a trade organization or a common market; it is a guarantee of democracy, freedom, justice, and human rights. Nations cannot stay in the E.U. if they do not respect these guarantees.