By Antonio Pollio Salimbeni
"An arc of instability surrounds the European Union." Terrorist attacks, extremist groups exploiting porous borders, migration, and destabilising actions by Russia: this is the extremely worrying context outlined in the document - which Europolitics had access to - prepared by the EU's High Representative for Foreign Affairs and Security Policy, Federica Mogherini, for the European Council of 25-26 June. At their summit, the heads of state and government should confirm Mogherini's mandate to develop the EU's…