Denmark's Reintroduction of Border Controls in the Schengen Area

More than 10 years after it joined the Schengen area allowing free movement across fellow European states, Denmark has recently put up border controls. The announcement surprised its neighbours Germany and Sweden. Why has Denmark made this move? What is it scared of? In Reporter we look at a country seen as a model of tolerance, that has now been tempted by isolationism. http://www.euronews.net/