LONDON (Reuters) - Britain said it was unconditionally committed to maintaining European security, in a document on Tuesday setting out details of the relationship it wants to have with the European Union after Brexit. The document set out a number of areas where Britain wanted to maintain or deepen cooperation on security. It said the government could offer to continue  classified information exchange to support external action  with the EU, once negotiations with Brussels move on to future ties with the bloc.  The UK is unconditionally committed to maintaining European security,  the paper said.  In tackling the diverse, changing threats we all face today, it is in the interests of both the EU and UK that we ensure cooperation on European security.   