The EU's enlargement chief has issued a stark warning that the bloc's credibility and security are at stake as foreign powers seek to disrupt the process of new members joining. Brussels, April 16 /Agerpres/ - The European Commissioner for Enlargement, Marta Kos, is expecting great progress in the European Union's enlargement during the next years, but warned of external forces seeking to disrupt the process. 'For the first time in the history, we are somehow confronted with the external