Temporary Reintroduction of Border Control (ec.europa.eu)
"The reintroduction of border control at the internal borders must remain an exception and must respect the principle of proportionality. The scope and duration of such a temporary reintroduction of border control at the internal borders is limited in time and should be restricted to the bare minimum needed to respond to the threat in question."
Is EU's Schengen border-free dream at an end? (bbc.com)
"Greece has been told by the European Commission that it's failing in its duty to protect Europe's external frontier. And European leaders have warned that there are just weeks to "save" Schengen."
How to save the Schengen Zone (foreignpolicy.com)
"In a very practical sense, the ability to pass from sovereign state to sovereign state freely without showing a passport is a core success of the European Union's unique system of twenty-first century governance."
Croatia and Hungary: war of words over migration (politico.eu)
"Thousands of migrants have entered Austria amid increasingly bitter rows between central European countries."