Polish Prime Minister Donald Tusk will announce details of the planned security reinforcement of his country’s eastern border on Monday. The plan, called Protective Shield East, envisages investments totalling the equivalent to about $2.5 billion to secure the border, which is also forms part of the European Union’s external border. Poland, a member of NATO, has an eastern border with Ukraine, which is under attack from Russia. Poland also shares a border with authoritarian Belarus, an ally of Moscow, and the Russian exclave of Kaliningrad. In the course of the war in Ukraine, fears have grown…