Strong control of borders is needed to keep the country secure  Terrorism is often considered the biggest security threat to the UK. Ian Duncan Smith has argued that being in the EU “exposes UK to terror risk” because an “open border does not allow us to check and control people”. [1] The Schengen agreement on the free movement of people makes it easier for terrorists to move about in Europe as shown by the terrorist attacks on Paris which were planned in Brussels.  [1] ‘Staying in EU 'exposes UK to terror risk', says Iain Duncan Smith’, BBC News, 21 February 2016,