The expanding Schengen area does not make it more difficult to police due to the lack of border controls. Anyone attempting to enter the Schengen area will be checked at least once, this is exactly the same as anyone entering an individual country. Americans do not consider themselves less safe because they do not have border posts between Maryland and Virginia. The key therefore is not to dissolve Schengen but to ensure that all countries border police are of equally high quality and that they share information as is being done through the Schengen Information System (SIS) [1] and Europol.  [1] Schengen Information System, Wikipedia,